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Anthony1968

"Angle of Attack" on final approach

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It's not as if I have noticed this for the first time but I would appreciate a brief explanation to the following query.Apologies if I am in the wrong forum.

 

Why do large aircraft ( e.g A320) approach the runway on finals in a "nose-up" configuration as opposed to smaller aircraft, ( e.g C172) and some "medium" ones ( ATR 72) which approach in a "nose down" configuration until entering the flare? Also, ( I hope this doesn't sound silly) to the untrained eye there is no noticeable flare in the larger jets as they touch down on the runway as opposed to the C172 in which the flare is quite obvious and deliberate..........so does an A320 enter a flare at the TDZ???

 

I understand that it would be very difficult to "rotate" a large jet into a flare so close to the runway but is that the only reason for the "nose up" approach.

 

 

In fact when flying in a A320/B738 ( passenger unfortunately) the "pitch up" attitude becomes obvious in the cabin as the flaps are extended and the plane slows down on the approach.

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A very simple answer would be that the wing of passenger jets are designed to be flown at much faster speeds at much higher altitudes than small props.

 

Regards,

Ró.

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A very simple answer would be that the wing of passenger jets are designed to be flown at much faster speeds at much higher altitudes than small props.

 

Regards,

Ró.

 

So therefore the angle of attack has to be increased to keep flying at low speeds?????

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Just a note here but for future reference, I think you may have muddled up AOA and Pitch. On a very simple scale, pitch being degrees above the horizon, and AOA being the difference between the angle of the wing against the horizon and the angle the motion of the aircraft makes with the horizon through the air. Eg. Level flight, pitch of 3 degrees nose up would be an AOA or 3 degrees, or an angle of climb 1 degree, and a pitch of 5 degrees nose up would give an AOA of 4 degrees. Okay I probably was clear as mud, but here's a wikipedia article for you on the subject:

http://en.wikipedia.org/wiki/Angle_of_attack

 

Regards,

Ró.

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I fly one of the aircraft you listed, the ATR 72.

 

For landing we can only flare to around 7 degrees above the horizon because we strike the tail at 10. That is one problem of a short landing gear and a long fuselage. On the baby Dash-8 we could flare to 14 degrees.

 

Funny thing is with a no flap landing if there is loss of hydraulics then we have to land 10 knots above our tire speed with minimal flare. Makes for an interesting approach and landing.

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Hi!

 

I'm not a real pilot by any mean but what I'm kinda thinking from what the above post said is that very basically speaking for their size airliner wings generate a lot less lift than small GA wings because airliners fly a lot faster so don't need such big wings for their size? However when flying slow the airliner needs to compensate so will approach in a nose-up attitude to descend on a final approach while a small GA on the same finals will be generating a lot more lift for it's size so will be nose-down?

 

Also GA aircraft I think approach at 60kt and cruise at 100kt (well a C172 in FsX does!) which is only a small difference whereas an airliner will approach at 135kt but cruise at 450kt which is like 3 or 4 times the difference. Maybe that has something to do with it too but I really don't know?

 

As for the flare I have no idea. One thing I noticed watching real airliners landing is that they seem to make really nice touchdowns all the time (except in really bad weather). But in Fs when I fly to the runway and pull the power back the aircraft just drops onto the runway like a stone. This makes me look bad in instant replay for both GA and airliners and as yet I haven't been able to figure out a better way of doing things!

 

Anyway sorry I don't have any real world info but those are my thoughts from simming for what they're worth!!

 

Many thanks.

 

P.

 

P.S. I also have a vague thought of seeing a smaller regional jet or two (I think Crj's) coming into airport with a nose-down attitude. I don't know why that would be either (if I'm not imagining it!)

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I fly one of the aircraft you listed, the ATR 72.

 

For landing we can only flare to around 7 degrees above the horizon because we strike the tail at 10.

You should see how our regional devision flies their ATR 72's, You'd swear the notion of a nose up attitude landing never occured to them, frequently landing either on the nose gear, or all three at once.... :huh:

 

http://www.youtube.com/watch?v=MpWERNCULVc

 

Regards,

Ró.

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@Ró............thanks for that, I need to do some reading but I understand the difference now ( I think)

 

@ Cessnaflyer...........I have seen some very interesting landings by ATR's ( EICK , my local airport) in heavy crosswinds. In fact some look positively scary.

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Also, ( I hope this doesn't sound silly) to the untrained eye there is no noticeable flare in the larger jets as they touch down on the runway as opposed to the C172 in which the flare is quite obvious and deliberate..........so does an A320 enter a flare at the TDZ???

 

I understand that it would be very difficult to "rotate" a large jet into a flare so close to the runway but is that the only reason for the "nose up" approach.

 

Sorry for skipping that part, we certainly flare out A320's, B737's, A330s ect, depending on aircraft type about 8'-20' above the runway.

 

Regards,

Ró.

 

@ Cessnaflyer...........I have seen some very interesting landings by ATR's ( EICK , my local airport) in heavy crosswinds. In fact some look positively scary.

I'd bet so, ORK can get quite bothersome at times with it's wind, and it's fog. Whoever allowed it to be built there really should hang their heads in shame....

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You should see how our regional devision flies their ATR 72's, You'd swear the notion of a nose up attitude landing never occured to them, frequently landing either on the nose gear, or all three at once....

 

The landing gear is one of my least favorite aspects of the aircraft. The Dash had, IIRC 23 feet and the ATR only has 13'6" between the gear. The ATR has no rudder nosewheel steering. It is going to be funny watching us takeoff and land for the first few weeks.

 

The ATR is a crazy airplane to fly from what I am finding out in the sim. The single engine climb rate is about 300 fpm and it takes a LONG time to get to acceleration altitude! With icing conditions forget it. Good we will be flying them around Hawaii!

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The landing gear is one of my least favorite aspects of the aircraft. The Dash had, IIRC 23 feet and the ATR only has 13'6" between the gear. The ATR has no rudder nosewheel steering. It is going to be funny watching us takeoff and land for the first few weeks.

 

The ATR is a crazy airplane to fly from what I am finding out in the sim. The single engine climb rate is about 300 fpm and it takes a LONG time to get to acceleration altitude! With icing conditions forget it. Good we will be flying them around Hawaii!

Oh deary me, doesn't sound fun at all. We've been having MORE than our fair share of engine failures in our ATRs, (when I say we, I mean Aer Arann, a separate entity operating on behalf of us for regional flights), just take a look at the AV Herald and it's littered with things. FOUR engine failures so far this year and the fleet only has 12 aircraft!!! :O A real pain for us as it's really damaging our reputation for punctual safe flights seeing as everyone sees the same livery and thinks we're one in the same... The ATR was taken out of service in northern USA after the Roselawn accident am I correct? Hopefuly you'll never come across ice in Hawaii or else the postcards are lying... :P Though yee do have those hills to worry about, 300 fpm enough for you guys?

 

Regards,

Ró.

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It's not as if I have noticed this for the first time but I would appreciate a brief explanation to the following query.Apologies if I am in the wrong forum.

 

Why do large aircraft ( e.g A320) approach the runway on finals in a "nose-up" configuration as opposed to smaller aircraft, ( e.g C172) and some "medium" ones ( ATR 72) which approach in a "nose down" configuration until entering the flare? Also, ( I hope this doesn't sound silly) to the untrained eye there is no noticeable flare in the larger jets as they touch down on the runway as opposed to the C172 in which the flare is quite obvious and deliberate..........so does an A320 enter a flare at the TDZ???

 

I understand that it would be very difficult to "rotate" a large jet into a flare so close to the runway but is that the only reason for the "nose up" approach.

 

 

In fact when flying in a A320/B738 ( passenger unfortunately) the "pitch up" attitude becomes obvious in the cabin as the flaps are extended and the plane slows down on the approach.

 

When flying single engine, one of the overriding concens is engine failure, so you're trained to keep the runway within gliding distance in the traffic pattern. Inevitably, this leads people to make high, steep, power-off approaches. This gives the appearance of pronounced nose down approaches when watching SE planes land. If the pilot flew a shallow approach at final approach speed the way an airliner does, then you would see a more even attitude.

 

The reason you don't see the same kind of long flare in an airliner as you would in a SE propeller aircraft is because if you flared an airliner and held it off the runway until she touched down in a full stall, you would run out of runway and end up in a ball of wreckage. Jet aircraft have higher residual thrust at idle and much less drag than a propeller aircraft which has a big propeller disc up front. Jets would run out of runway before running out of speed in the flare. The technique for flaring a jet aircraft is to check the rate of descent just as you approach the ground while continuing to fly it onto the runway with the main goal being a touchdown at the touchdown aimpoint.

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Oh deary me, doesn't sound fun at all. We've been having MORE than our fair share of engine failures in our ATRs, (when I say we, I mean Aer Arann, a separate entity operating on behalf of us for regional flights), just take a look at the AV Herald and it's littered with things. FOUR engine failures so far this year and the fleet only has 12 aircraft!!! :O The ATR was taken out of service in northern USA after the Roselawn accident am I correct? Hopefuly you'll never come across ice in Hawaii or else the postcards are lying...

 

Regards,

Ró.

 

Yeah I am very worried about what is going to happen with these engines. It is the same type that is on the Dashes and we have had very few problems with them. Hopefully that streak will continue.

 

Yeah the American Eagle crash was the one that forced all of them down to routes in the south out of Dallas, Miami and San Juan. The first one we receive is from American Eagle hopefully they've taken great care of it.

 

Forgot to say we have a little connection now, Kahala Aviation of Dublin, Ireland has given us some funds now.

 

@ Cessnaflyer...........I have seen some very interesting landings by ATR's ( EICK , my local airport) in heavy crosswinds. In fact some look positively scary.

 

I can imagine what those guys are going through. It is one interesting aircraft in how they set up the flight controls.

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Yeah I am very worried about what is going to happen with these engines. It is the same type that is on the Dashes and we have had very few problems with them. Hopefully that streak will continue.

 

Yeah the American Eagle crash was the one that forced all of them down to routes in the south out of Dallas, Miami and San Juan. The first one we receive is from American Eagle hopefully they've taken great care of it.

 

Forgot to say we have a little connection now, Kahala Aviation of Dublin, Ireland has given us some funds now.

Kahala do leasing of old aircraft IIRC. I think something like half the worlds aviation leasing firms are based or have a base in Ireland, something about tax haven. Good to know you're sourcing aircraft finance from us anyways, nice connection to have, if you're ever over on Business I'll have to take you out and show you the city, drinks will be on me.... ^_^ Be wary of the older ATRS though, as I mentioned earlier, there are 2 we have that are 21 and 22 years old and they just love going tech. Hopefully you guys have a quick call out time for your MX crew.

 

Regards,

Ró.

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Hopefully you guys have a quick call out time for your MX crew.

 

:lol:

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So, that's.... a no? :rolleyes:

 

If we are in base it is great. Otherwise we have to get a rescue aircraft if we are at any other airports.

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If we are in base it is great. Otherwise we have to get a rescue aircraft if we are at any other airports.

By rescue aircraft do you mean your company jet (if yee have one, I know you said yee weren't all that big), or do you mean you have to charter in another aircraft to run the services?

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By rescue aircraft do you mean your company jet (if yee have one, I know you said yee weren't all that big), or do you mean you have to charter in another aircraft to run the services?

 

We usually have another aircraft do a flag stop along their route to pick up passengers and drop off parts and mechanics from base. It works ok since the island chain isn't too big.

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We usually have another aircraft do a flag stop along their route to pick up passengers and drop off parts and mechanics from base. It works ok since the island chain isn't too big.

Makes sense given the short nature of yeer routes. Must be nice operating in such a small environment, bet everyone knows everyone and there's a real team atmosphere?

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Hey all

 

Why do jets normally have a nose up attitude on approach and landing? I believe the answer is that as Ro said, the wing is designed for high speed and to be able to land at suitable airspeeds, the wing area has to be increased to allow for a slower speed and still generate sufficient lift to keep the aircraft airborne. So as the flaps are extended, there is a nose up pitch due to the increase in lift which is counter acted by trimming nose down, but there is still a distinctive nose up attitude. On approach the aircraft is descending towards the runway and the approach is controlled by pitch and power ie control the rate of descent. There are speed requirements as well, so they are all controlled by pitch and power. Closer to the threshold the speed has reduced and to maintain the rate of descent and speed the nose comes up a bit more and then as Ro said, flare at a certain height above the runway to arrest the rate of descent. The same principle of attitude + power = performance is just as relevant to other aircraft as well.

 

Anyway thats what I was taught when I learnt to fly in the military and I hope it makes sense

 

Craig

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It is going to be funny watching us takeoff and land for the first few weeks.

 

Chris, since my local airport is only operated by ATR42 and SAAB 340, I've been on these quite a few times. Usually everything about them is very undramatic, but in May I experienced a landing in the ATR that was a bit different. It was a nice day with no winds and the approach was nice and stable. But once the nose wheel made contact with the tarmac we started wobbling from side to side really violently in our seats for about 7-8 seconds. Would the reason most likely have been the short wheelspan and perhaps a new pilot? Even my landings in the Skyranger UL are usually more stable than that! :D

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Chris, since my local airport is only operated by ATR42 and SAAB 340, I've been on these quite a few times. Usually everything about them is very undramatic, but in May I experienced a landing in the ATR that was a bit different. It was a nice day with no winds and the approach was nice and stable. But once the nose wheel made contact with the tarmac we started wobbling from side to side really violently in our seats for about 7-8 seconds. Would the reason most likely have been the short wheelspan and perhaps a new pilot? Even my landings in the Skyranger UL are usually more stable than that! :D

 

The gyrations can be from several different things. All airlines do things slightly differently even with the same aircraft so depending on procedures this may be different.

 

One way could be that once they touched down and the captain went to grab the tiller he could have bumped it and that started the swerving back and forth. Other ways we have seen are when one engine is slightly slower to go into reverse and it knocks the plane out of balance and the third way would be not depressing the brake pedals equally on the rudders.

 

The ATR is a beast to control on the ground because it has no nose wheel steering with the rudder pedals, only the side tiller can move it.

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The ATR is a beast to control on the ground because it has no nose wheel steering with the rudder pedals, only the side tiller can move it.

Out of interest Chris, wouldn't you always be using the tiller for turning anyway? If you're still at high speed the rudder should be more than enough to turn aerodynamically. I mean, the only time I'd use rudder steering would be for keeping it straight on a straight stretch of taxiway while I need my left hand for something. Can I take it from your post that your airline allows FOs to Taxi the aircraft?

 

Regards,

Ró.

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Out of interest Chris, wouldn't you always be using the tiller for turning anyway? If you're still at high speed the rudder should be more than enough to turn aerodynamically. I mean, the only time I'd use rudder steering would be for keeping it straight on a straight stretch of taxiway while I need my left hand for something. Can I take it from your post that your airline allows FOs to Taxi the aircraft?

 

Regards,

Ró.

 

Nope only captains taxi. During the takeoff roll you have no rudder authority until around 70 knots and even at that speed if there is a gust of wind the captain will have to get back on the tiller or the FO a push of the downwind brake. The rudder is also a flying design that doesn't move itself but relies on a tab to move the whole rudder, much like the MD80's flying tail. Below ~70 knots the only directional control is provided by differential braking or the tiller.

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