Airborne Early Warning & Control: News & Discussion

Gagan · Post by **Gagan** » 05 Feb 2011 09:52

Here is a picture that shows the approximate angles involved

uddu · Post by **uddu** » 05 Feb 2011 10:16

http://www.deccanherald.com/content/111 ... ystem.html
According to Prahlada, the Indian AEW&C is an Active Phased Array Radar, derived from indigenous effort to "look some few hundred km" 360 degrees by rapidly scanning the area around it for airborne and ground threats.

chackojoseph · Post by **chackojoseph** » 05 Feb 2011 16:25

shiv wrote:
Cybaru wrote:You are always going to have blind spots somewhere on the platform even on those that claim 360 degree coverage. Think about it.
Absolutely. In fact "full coverage" would be a sphere with the AEW aircraft at the center. This is not achievable by one aircraft.

It can be. But, pure waste of time and resources. I had asked the same Q to CABS. It can be done by smaller antennas. The software will add extra lines of codes. Extra power etc.

vic · Post by **vic** » 06 Feb 2011 20:06

Awacs or AEWs normally fly Figure "8"s, so the blind side gets covered every couple of minutes!

Singha · Post by **Singha** » 06 Feb 2011 20:24

even a zig zag would periodically sweep the blind areas fore and aft. in reality at 250km away the base of the cone with its apex at the radar is very wide...

vic · Post by **vic** » 06 Feb 2011 21:01

Flying in figure "8", the blind spot can be covered every 45-75 seconds.

rakall · Post by **rakall** » 06 Feb 2011 21:13

Rakall post from BR (AeroIndia 2007)

1. Each time 120deg coverage. A/c turns around for 120deg from other side.1280 modules switched over from one side to the other as required with a switching mech
2. 360deg coverage possible, but restricted only by payload constraints – IAF asked for a lot of systems. Including all that meant only this much could be put into arrays. If 360deg coverage required – we can put some antennas at front and back. 3. 65*8*160 watt peak power, 0.07*peakpower = AvgPower (7% duty cycle)

4. Data transfer to 40a/c @ 64kbps VHF/UHF 300km range. LOS. Only info (target coords, speeds etc in a pre-set format), no pictures.
5. Satcom to ground station – no range limitation. No LOS limitations.
6. Array – S band, IFF – L band (250w amplifier) 500km range for IFF at sides(250km range front & back)
7. 5hrs endurance w/o IFR
8. Cooling by natural convection
9. AA, A2G, A2C modes exist. Inter-leaving doesn’t exist. If end user asks – can be done. Needs a simple switching mechanism.
10. 5 operator consoles.. toilets are there

CABS AEW&C project has 10 senior IAF officers working with the CABS/LRDE group to reduce the communicatio/expectation gap between the development agency & enduser.

...

4years later we are still discussing the same thing without referring to the BR archives.... Please see above quoted text -- a post from AeroIndia2007.

The mission profile of the CABS AEW&C is that:
1. It will supplement the Phalcon AWACS
2. it will fly parallel to the border with one side of the antenna looking across the border..

so essentially it is covering what is required on the other side of the border... No necessity to sweep inside our own side of the border... so it will fly parallel to the border (at a safe standoff distance) with one side of the array active, then at the end of the area of interest - it will turn around and switch on the other side antenna array...

Normally in a mission you are never flying ahead into the border as that gives you the shortest possible time before it has to turn around.. (the risk of crossing the border is more when flying ahead into the border).. Even in a mission where it has to sweep both sides simulatenously - the 240deg coverage is not continous.. it is one side 120deg , then other side 120deg and so on..

CABS can put secondary antenna's to cover the 360deg - if required.. but that will add to mission weight and reduce endurance.. To accomodate all the systems that IAF requested -- there was no possibility of additing fore-and-aft antennas to cover the blindspot... and this was done with fully taking IAF into confidence..

Gagan · Post by **Gagan** » 06 Feb 2011 22:16

The bigger birds like the Phalcon work on different philosiphies.

They are battlefield controllers, capable of seeing and directing entire battlefields on the ground and on the air. Naturally they have a lot more controllers, a lot of electronic equipment, the needed electrical and electronic power, and yes 360 degrees coverage.

The Phalcon has three huge AESA radars in an equilateral triangle inside its radome. The radars don't rotate, the radar beams are electronically controlled, and the base of the radar faces forward and the apex in the direction of the tail.

The smaller AEW&C are essentially gap fillers which can rapidly take control of smaller areas or gaps in the picture, much more swifter, are much more economical to operate, and so consequently they have a small crew, less operating stations on board.

D Roy · Post by **D Roy** » 06 Feb 2011 22:18

The CABS AEW&C is more than a gap filler.

Gagan · Post by **Gagan** » 06 Feb 2011 22:21

But I do have one question of my own.

Do older generation radar receivers need to have a radar signal present for a certain duration before they can identify its presence?

I don't know from where, but I understand that with an AESA radar, if the enemy's radar installations are known, the AESA can restrict its signals in those areas, so that the enemy won't even know that a radar is around. The trick here is that the AESA scans the entire area so quickly that it is able to identify and repeatedly scan the enemy and shifts its beam very quickly without tripping the enemy's radar warning receivers.

How true is this?

chackojoseph · Post by **chackojoseph** » 06 Feb 2011 22:41

Indian AEW&C

DRDO’s Active Array Antenna Unit (AAAU) or the Primary radar is designed to have a range of 200 kms for 2 sqm target as per the OR by the IAF. In international comparison table it translates to 5 sq meters target or RCS can be detected at a range of 300 kms in normal mode of operations and 375 kms for extended modes, i.e. while not looking 240 degree all the time.

D Roy · Post by **D Roy** » 06 Feb 2011 23:21

Do older generation radar receivers need to have a radar signal present for a certain duration before they can identify its presence?

I don't know from where, but I understand that with an AESA radar, if the enemy's radar installations are known, the AESA can restrict its signals in those areas, so that the enemy won't even know that a radar is around. The trick here is that the AESA scans the entire area so quickly that it is able to identify and repeatedly scan the enemy and shifts its beam very quickly without tripping the enemy's radar warning receivers.

LPI.

But we must remember that even AESA's do have trouble "near the edge".

Mechanically steered arrays of course give you that tell tale glint.

PratikDas · Post by **PratikDas** » 06 Feb 2011 23:24

Gagan wrote:But I do have one question of my own.

Do older generation radar receivers need to have a radar signal present for a certain duration before they can identify its presence?

I don't know from where, but I understand that with an AESA radar, if the enemy's radar installations are known, the AESA can restrict its signals in those areas, so that the enemy won't even know that a radar is around. The trick here is that the AESA scans the entire area so quickly that it is able to identify and repeatedly scan the enemy and shifts its beam very quickly without tripping the enemy's radar warning receivers.

How true is this?

This is plausible. Assuming the source and the target have the same RCS, the same radar frequency and the same output power, the radar with the better receive sensitivity can transmit a shorter ping to evade the target's receiver.

Assuming similar technology is used in the T/R modules of both radars, the AESA with the greater number of receive modules elements will have the better receive sensitivity. However, there is a catch with this approach. To halve the duration of the output pulse for better evasion, thereby halving the output energy, you'd have to double the receive sensitivity, and therefore double the number of receive modules. Not very practical.

A better approach would be to keep the output energy constant by doubling the output bandwidth and power while halving the pulse duration. To do this, however, you need better technology in the transmit and receive modules because you have contradicting goals, i.e. what's called the gain-bandwidth product. GaN and X-band would serve better than GaAs and lower bands.

On a separate note, the more transmit elements you have in the antenna, the more muted regions, or nulls, you have in the output beam pattern. Beamforming and beam-steering is used to direct those nulls at direction of choice, say a known receiver. Incidentally, beam-steering is also used when an AESA on a mobile platform needs to keep focus on a stationary target:

rakall · Post by **rakall** » 06 Feb 2011 23:47

nukavarapu wrote:^^^ Thanks rakall, that was a very informative posts. I have a very novice question, so please let me know if that question qualifies for the newbie thread. The module shifting from one side to another, is that the case with all AESA AEWCS aircrafts including Phalcon, Sentry etc? Of the bigger systems provide a continuous dual side performance? I am just trying to understand the industry norms.

there was an animation of the Phalcon beam sometime ago on BR.. Even in Phalcon in normal mode of operation -- the 360deg is not illuminated at the same time.. the beam basically goes from one edge of the equilateral triangle to the other sequentially - in one full rotation, the 360deg picture is complete.. (basically what matters here is the time period of the beam - the time taken for the beam to come back to the same point.. i guess the time to complete is short enough to be acceptable)..

if you are illuminating all the modules corresponding to the 360deg at the same time -- the total power available is distributed over all of them.. therefore, power per module reduces drastically and the detection range reduces too..

Normally there is no utility of having a reduced range steady-state 360deg picture.. what is most beneficial is the long range detection (at 300km plus range) -- and then you have vectored your Mig29's & Su30MKI's to the threats... basically the detection range drops off significantly with power available per module and that is probably less important when compared to the distance a fighter can travel in 2-3secs (less than 0.3Km) which is typically the beam time period..

so there is no advantage of having 360deg illumination with less power per module on a Phalcon when a threat fighter would have advanced less than 0.3km in the typical refresh time of 2-3seconds.. .. Whereas by having all three antennas illuminated instead of one, you reduce power density by 1/3rd and reduce detection range from 300km to 100km.. WHich is better? There lies the answer.

vic · Post by **vic** » 07 Feb 2011 10:15

Note the 360 degree coverage issue arising from "conventional" radars adopted in US E-3s and E-2s. These radar used to rotate slowly, first detecting and then tracking. Data used to be built up after number of sweeps, which could take anything from 30 sec to couple of minutes. Hence blind area would not get covered for many minutes. This thing is done By AESA on the fly, almost instantaneousy, so when the AEW is flying figure 8s, it does not lose the image and tracks in blind area for more than a few seconds, which is immaterial.

P Chitkara · Post by **P Chitkara** » 07 Feb 2011 13:23

Will the data transfer rate @64kbps be sufficient for our future needs. Looks somewhat on the lower side.

I guess this should be scaleable as we move ahead and be a non issue.

Singha · Post by **Singha** » 07 Feb 2011 13:36

> Flying in figure "8", the blind spot can be covered every 45-75 seconds.

but would they do that in real life? seems to me when doing the turns the people moving around (like the chief controller) might need to take their seats. and '8' is a nearly constant curve....perhaps a long nascar type racetrack is more like it?

Arya Sumantra · Post by **Arya Sumantra** » 07 Feb 2011 18:38

Since the blind spot is only a small angle, actuators could be combined with the supports of L-star to give it rudder-like angular deflection. Any resulting undersirable yaw movements could be counter-balanced by FCS through the rudder.

JMT

vic · Post by **vic** » 07 Feb 2011 18:45

Singha wrote:> Flying in figure "8", the blind spot can be covered every 45-75 seconds.

but would they do that in real life? seems to me when doing the turns the people moving around (like the chief controller) might need to take their seats. and '8' is a nearly constant curve....perhaps a long nascar type racetrack is more like it?

AEWs don't fly staright lines, its either 8s or Os.

Cybaru · Post by **Cybaru** » 08 Feb 2011 03:36

Singha wrote:> Flying in figure "8", the blind spot can be covered every 45-75 seconds.

but would they do that in real life? seems to me when doing the turns the people moving around (like the chief controller) might need to take their seats. and '8' is a nearly constant curve....perhaps a long nascar type racetrack is more like it?

You are not turning and doing 8's every 2 minutes. There is a wide area where this pattern is performed, depending on what area of interest you are covering. It will be a whole bunch of air sick operators vying for one toilet...

Juggi G · Post by **Juggi G** » 08 Feb 2011 06:43

NRao · Post by **NRao** » 08 Feb 2011 07:09

What is that lobe on the side?

Hope they have a dynamite network system in place.

Gagan · Post by **Gagan** » 08 Feb 2011 08:42

Shouldn't the pattern be more like a series of small 'S' which then becomes the '8' or the 'O' pattern.

Just using the rudder won't cause any / much airsickness in the crew.

But then we seem to be nitpicking, its not like the AEW is the only friendly Radar out there. There are numerous ground based, Blimp based and other radars in the air - hopefully all networked, with the CABS AEW and the Blimp forming a node.

Kalle · Post by **Kalle** » 08 Feb 2011 09:19

You typically want to minimize time spent turning with an AEW&C, not due to the comfort of the operators but for the simple fact that the bank required points the radar down in the ground and up in the sky. Instead you want to keep it looking at normal flight altitudes and the surface towards the horizon.

Instead some sideslip can increase the coverage if needed, but because of the distance from the battlefield it normally is stationed at you get a coverage so wide that it hardly is necessary.

Zynda · Post by **Zynda** » 08 Feb 2011 18:15

Just went through "Airborne Surveillance" seminar at Aero-India NIC website (awesome show by NIC...quick buffer and good resolution videos. Great job guys!)

AVM PP Katarki CABS,DRDO
“Indian AEW&C System: Development through Networking Knowledge Sources”

Role of Indian AEWC is to detect, track, command & control system...act as an compliment to Phalcon system .

Salient features of the system:
• AEW&C has AESA
• Self protection suite from DARE consists of RWR, MAWS, CMDS
• Platform has 2 APU, additional cooling packs (I think in total 3)
• In-flight refueling probe
• 59 different antennas mounted on the airframe.

Differences b/w Indian systems and comparable systems mounted on Embraer platform
• Has elevation scan to overcome aircraft banking problems - limited to 7-10 deg
• Has IFF Mk.12 with S-mode capability (S-band is indigenous while high capacity L-band is imported)
• 360 deg coverage ESM
• COM Support Measure (CSM) and recording ability for offline analysis
• High capacity C-band datalink for Line of Sight air-ground & ground-air transmission
• Beyond LOS SatCOM of similar capacity
• 7 VHF sets...provides data & voice.
• Up to 5 operator Work Stations
• In-flight refueling probe...has seats for refueling crew as well

Whole system will be in compliance with FAR 25 and Embraer is responsible for getting the certification. First platform with dummy AAAU is expected to roll out from Embraer facility on Feb 21 2010. Flight campaigns to certify the system will be undertaken at Brazil. CEMILAC is responsible for functional certification of the system. As the first platform arrives in India, dummy AAAU will be replaced by actual one. Further flight tests will be undertaken to validate the system. IAF has been involved in the project at grass roots level. Apparently, IAF helped a lot to establish algorithms for detection, interception & pursuit protocols. A lot of ground systems to simulate, fabricate & validate these avionics have been established.

I am just posting highlights. Hopefully Rakall will provide a much more professional & comprehensive report on the same

Karan M · Post by **Karan M** » 08 Feb 2011 19:24

Zynda wrote: • Has IFF Mk.12 with S-mode capability (S-band is indigenous while high capacity L-band is imported)

Basically said:
Primary Radar - S Band Tx/Rx and other systems, all developed indigenously. Modules for Tx/Rx made by Indias Astra

IFF - L Band
Indigenously designed and developed by CABS, including antenna, processing, algorithms etc, only L Band high power transmitter was imported off the shelf

rakall · Post by **rakall** » 09 Feb 2011 02:02

rakall · Post by **rakall** » 09 Feb 2011 02:03

Indian AEW&C System, AVM PP Katarki, CABS,DRDO

Many points Zynda seems to have already captured in his post.. Also refer to his post for completeness .

Role specified by IAF – detect, track and act as a command & control function complementing the bigger IL-76based system.

-Primary radar with added elevation scan to overcome banking problems (7-10deg)
-IFFmk12 with S-mode capability (mode4, modes, level2 interrogator developed inhoise except for the high-power L-Band amplifier which is imported)
-360deg ESM
-CSM & CSM recording for offline analysis
-C-band highcapacity datalink for LOS A-G & G-A; Ku-Band Satcom for non-LOS
-7 V/UHF sets with data & voice – 5for operators & 2 for flight crew
-5OWS (additional flight seats for additional set of crew), IFR

There is a comparison slide of how the systems on CABS AEW&C against what is there and what is missing on similar systems around the world.. As you can see the indigenous AEW&C system has all of it, where as other systems around the world is missing some systems in their architecture. (refer to the picture poster of the slides). (This to me signifies two things – while the others have made some design compromises, the IAF wanted all the systems on it – a clearcut case of IAF brochiritis, and also why there is no space/weight left to accommodate antennas for fore/aft coverage.. thankfully IAF made that compromise & did not ask for 360deg coverage)

Certification responsibility lies with Embraer (platform along with dorsal unit).. Close co-operation between Embraer & CABS team for all the real estate management, CG management etc stressed. IAF, CEMILAC etc are always in loop at every stage while affecting any changes/modifications. First AAAU (mass & CG equivalent dummy) handed over to Embraer, rollout in 21 Feb2011. The electronic AAAU will be ready by the time Embaraer finishes flight tests of the airframe.

-Aerodynamic & Inertial loads at different points in the operating envelop estimated from windtunnel and passed on to Embarer.
-8.24m long dorsal unit tested for lighting protection (high voltage & high current modes)
-T/R module technology is prone to denial. It not only has to be designed & mass produced but has to be flight qualified, airworthiness certified, air cooled etc – we have been able to do it all in-house (with help of Astra Microwave, Hyd)

AAAU unit already tested for transmission & reception from rooftop against opportune & assigned targets – which means they tested it against normal Bangalore flight traffic, as well as some specific experiments where they flew certain a/c with a view to test the system performance. Tested in target crossover mode, multiple targets, highly manoeuvring targets already.
-All individual systems tested in standalone mode on AVRO platform. IFF tests on AVRO proved the Range, azimuth accuracy, scan time & coverage.
-ESM & SPS under integration.
-IAF is still evolving its concepts of battle management, command & control (I think they will evolve as the experience with operating the Phalcon build-up).. the IAF team embedded at CABS acts as a continuous conduit for two way transfer of information... the algorithms for intercept based on collision, pursuit and offset are being developed and under validation.. the IAF team along with fighter controllers evaluate and clear these.. the software is being developed in 3-4builds with added functionality along the way.. Look into the picture poster that I wil post. One of the simulation scenarios where a AEW&C detects a F16 and about to vector a Mig29 on to that.

In the concluding remarks after the talk, Dr.K.Thamilzmani, CEMILAC remarks that the program is on schedule.

For completeness & records, adding up a post from AeroIndia2007

1. Each time 120deg coverage. A/c turns around for 120deg from other side.1280 modules switched over from one side to the other as required with a switching mech
2. 360deg coverage possible, but restricted only by payload constraints – IAF asked for a lot of systems. Including all that meant only this much could be put into arrays. If 360deg coverage required – we can put some antennas at front and back.
3. 65*8*160 watt peak power, 0.07*peakpower = AvgPower (7% duty cycle)

4. Data transfer to 40a/c @ 64kbps VHF/UHF 300km range. LOS. Only info (target coords, speeds etc in a pre-set format), no pictures.
5. Satcom to ground station – no range limitation. No LOS limitations.
6. Array – S band, IFF – L band (250w amplifier) 500km range for IFF at sides(250km range front & back)
7. 5hrs endurance w/o IFR
8. Cooling by natural convection
9. AA, A2G, A2C modes exist. Inter-leaving doesn’t exist. If end user asks – can be done. Needs a simple switching mechanism.
10. 5 operator consoles.. toilets are there

CABS AEW&C project has 10 senior IAF officers working with the CABS/LRDE group to reduce the communicatio/expectation gap between the development agency & enduser.

Baldev · Post by **Baldev** » 09 Feb 2011 02:05

i hope they also build ground based and naval aesa radar using this tech

SriSri · Post by **SriSri** » 09 Feb 2011 05:40

Northrop Grumman Confirms RFIs Issued for Naval Airborne Early Warning Aircraft

From a press briefing on 7th.. Sorry for the delay in publishing..

Avinandan · Post by **Avinandan** » 14 Feb 2011 01:10

CABS AEW Cabin View

The sitting arrangement of controllers/operator consoles doesn't look to be optimal here IMVHO.
It would have be better that if the operator consoles could have been placed facing outwards to the fuselage/window in a line, so that the commander can roam in between and could see two or more consoles if needed.

Sitting arrangement of Erieye in Saab 2000 is what I am talking about :--
http://tinyurl.com/Saab2000-Erieye

Gurus, please provide your thoughts on this.

Raja Bose · Post by **Raja Bose** » 14 Feb 2011 02:04

^^But in that case how would one operator be able to lean over and look at the funny joke in the neighbouring operator's Yahoo messenger chat window?

Rahul M · Post by **Rahul M** » 14 Feb 2011 02:06

^^^ this is the BEST possible arrangement.

this is what you get when you put an arrangement according to your ideas on the EMB-145.

the pic is of a greek EMB-145 AEW.

http://forum.keypublishing.co.uk/showpo ... stcount=44

I don't get why you think you can tell from a pic what is optimal or not and the designers who do these things day-in and day out, have decades of experience and IAF input besides are dumb. please, your posts are sounding very silly.

Raja Bose · Post by **Raja Bose** » 14 Feb 2011 02:09

Rahul M wrote:

In fact you can see one of the supervisors and operator discussing Tetris playing strategies in an uncomfortable manner.

Indranil · Post by **Indranil** » 14 Feb 2011 02:56

Rahul M wrote:^^^ this is the BEST possible arrangement.

this is what you get when you put an arrangement according to your ideas on the EMB-145.

the pic is of a greek EMB-145 AEW.

http://forum.keypublishing.co.uk/showpo ... stcount=44

I don't get why you think you can tell from a pic what is optimal or not and the designers who do these things day-in and day out, have decades of experience and IAF input besides are dumb. please, your posts are sounding very silly.

Actually quite right. I have been the ERJ-145. I am 5'11'' tall. The only place where I could stand straight was the center of the plane (about the 2 feet wide alley). With such a narrow body, the ceiling tapers off quiet fast.

NRao · Post by **NRao** » 14 Feb 2011 04:21

I have been the ERJ-145. I am 5'11'' tall. The only place where I could stand straight was the center of the plane (about the 2 feet wide alley). With such a narrow body, the ceiling tapers off quiet fast.

Must have been a civilian ERJ-145.

http://upload.wikimedia.org/wikipedia/c ... .cabin.jpg

They are designed for that specific need.

Even in the Greek solution, I am not sure what is behind those guys that are standing, but there has got to be something that is of such great importance that these guys have to endure such rides. I do not think they would design it so that they bend that way all the time.

Having said that, I would still go for the IAF solution from a convenience point of view. For the simple reason today's networks provide FAR more alternatives than the ones build even a few years ago. A commander - I would hope - no longer needs to hover over any of the consoles. He should be able to get critical information piped straight to one of his own or which ever console he is at. Or some such other type of an option.

The Phalcon - I hope - has a 7'x5' latest display for the commander.

Karan M · Post by **Karan M** » 14 Feb 2011 04:24

Avinandan wrote:CABS AEW Cabin View

The sitting arrangement of controllers/operator consoles doesn't look to be optimal here IMVHO.
It would have be better that if the operator consoles could have been placed facing outwards to the fuselage/window in a line, so that the commander can roam in between and could see two or more consoles if needed.

Sitting arrangement of Erieye in Saab 2000 is what I am talking about :--
http://tinyurl.com/Saab2000-Erieye

Gurus, please provide your thoughts on this.

The Indian layout appears better. The commander can stand comfortably at the place where the "sena" appears on the fuselage and still see into all five Operator stations. He can also walk up and down easily. The Indian operators also have more space and its a less claustrophobic layout versus the Greek one, which is pretty cramped from ergonomic point of view, I really dont see it as optimal.

Indranil · Post by **Indranil** » 14 Feb 2011 06:15

NRao wrote: Must have been a civilian ERJ-145.

Yes, Ofcourse.

NRao wrote: http://upload.wikimedia.org/wikipedia/c ... .cabin.jpg

Don't about the height of the flight attendant in the pic. But imagine a decently tall man in that space.

Even a lady entering the craft has to stoop till she gets to the aisle

NRao wrote: Even in the Greek solution, I am not sure what is behind those guys that are standing, but there has got to be something that is of such great importance that these guys have to endure such rides. I do not think they would design it so that they bend that way all the time.

Actually there is nothing behind the standing men. The plane is about 4 economy seats wide. There is just 1 seat width of aisle behind the station-operators seat.

I think putting the equipment on one side is easier for means of wiring. But isn't it detrimental for the CG?

rgsrini · Post by **rgsrini** » 14 Feb 2011 06:44

I travel regularly in continental express jet (50 seat ERJ 145). It has 3 economy seats in each row. A typical row consists of a single seat on one side, the aisle and a 2 seater on the other side.

If you remove the luggage rack and move the aisle to the middle, it will be fairly comfortable for a 6 ft person to walk in the middle. Also, we are only discussing about the top half of the circular cross section in a plane.The bottom portion is available for all kinds of stuff including wiring. Considering that, evern wiring won't be a complex issue in this design.

I am personally convinced that this design has been made with everyone's comfort in mind.

Indranil · Post by **Indranil** » 14 Feb 2011 07:28

rgsrini wrote:I travel regularly in continental express jet (50 seat ERJ 145). It has 3 economy seats in each row. A typical row consists of a single seat on one side, the aisle and a 2 seater on the other side.

The reason i said 4 was because I counted the aisle as one seat.