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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.


Anthony O'Brien

 

 

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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.


Rónán O Cadhain.

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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?????


Anthony O'Brien

 

 

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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.


Rónán O Cadhain.

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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.


Chris Miller

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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.


Rónán O Cadhain.

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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.


Anthony O'Brien

 

 

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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....


Rónán O Cadhain.

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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!


Chris Miller

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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.


Rónán O Cadhain.

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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.


Chris Miller

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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.


Rónán O Cadhain.

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

 

:lol:


Chris Miller

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