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Tailstrike Avoidance  
User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Posted (9 years 3 months 3 days 16 hours ago) and read 3640 times:
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A post over in the Civil Aviation forum got me thinking....

During no-flaps landings in particularly long aircraft, such as the 777-300, A340-600, Q400, etc, what measures are taken to avoid tailstrikes?

The relatively nose-high attitude during landing must make this a real concern...


2H4





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15 replies: All unread, jump to last
 
User currently offlineNewark777 From United States of America, joined Dec 2004, 9348 posts, RR: 30
Reply 1, posted (9 years 3 months 3 days 14 hours ago) and read 3617 times:

Well, I believe that in at least the 773 there are computer controls that prevent the tail from striking, but I do not know much about the technology, or whether it is present in the other aircraft.

Harry



Why grab a Heine when you can grab a Busch?
User currently offlineCosmicCruiser From United States of America, joined Feb 2005, 2255 posts, RR: 15
Reply 2, posted (9 years 3 months 3 days 8 hours ago) and read 3506 times:

The pitch attitude is high but not to the extent that you would hit the tail. I always preface my statements by saying "from the jets I know" so most jets hit the tail somewhere around 10-12 deg. nose up. Eg. The MD-11 flight manual states that in a no flaps/no slats app. do not hold the a/c off and make a normal flare. Make only a small flare to arrest the sink and fly it on. Mainly this to prevent floating down the rnwy.

User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 3, posted (9 years 3 months 3 days 7 hours ago) and read 3510 times:

First of all, I don't think you'll find any of the aircraft you mention doing "no flap" takeoffs. There just isn't enough runway! So, that take care of the tail strike problem.

User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 4, posted (9 years 3 months 3 days 5 hours ago) and read 3469 times:
AIRLINERS.NET CREW
DATABASE EDITOR

Quoting PhilSquares (Reply 3):
First of all, I don't think you'll find any of the aircraft you mention doing "no flap" takeoffs. There just isn't enough runway! So, that take care of the tail strike problem.

I wasn't implying they would be performing no-flaps takeoffs. I was referring to tailstrikes during landing. American had a rash of tailstrikes during landing in the A300 several years back, mainly due to unstabilized approaches and bounce recoveries.

If a no-flap landing requires a higher deck angle during the flare, it seems the longer aircraft would be prone to tailstrikes during landing. Just trying to find out what measures are taken in these aircraft to prevent it from happening.


2H4





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User currently offlineAJ From Australia, joined Nov 1999, 2389 posts, RR: 24
Reply 5, posted (9 years 3 months 2 days 16 hours ago) and read 3378 times:

Hi 2H4, the 767 I fly is geometry limited in the -300 version.

The flight crew training manual mentions the following about tailstrikes on landing:
"A tailstrike on landing tends to cause more serious damage than the same event during takeoff.....the tail can strike the runway before the landing gear, thus absorbing large amounts of energy for which it is not designed."
The following factors are considered critical:
- Unstable approach,
- Holding off in the flare,
- Trimming in the flare,
- Mishandling of crosswinds
- Over rotation during go-around.

As for flapless landings the advise is minimal flare to avoid tailstrike. The manual then advises slight forward pressure to touch down in the correct zone.

A factor that we have seen on the line that has caused tail strikes is when the speedbrake lever is raised rapidly after a failure to auto-deploy. If the pilot flying is not prepared for the pitch up it can cause tail skid contact.

Cheers.


User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 6, posted (9 years 3 months 2 days 16 hours ago) and read 3366 times:
AIRLINERS.NET CREW
DATABASE EDITOR

Thanks for the info, AJ. That's exactly what I had in mind. Greatly appreciated.


2H4





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User currently offlineAndz From South Africa, joined Feb 2004, 8449 posts, RR: 10
Reply 7, posted (9 years 3 months 2 days 5 hours ago) and read 3313 times:
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some get pretty close on takeoff!


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User currently offlineKaddyuk From Wallis and Futuna, joined Nov 2001, 4126 posts, RR: 26
Reply 8, posted (9 years 3 months 1 day 22 hours ago) and read 3240 times:

I belive that the A346 anti-tailskid technology works on both landing and takeoff... but when it fails, its very easy to scrape the tail...


Whoever said "laughter is the best medicine" never had Gonorrhea
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17015 posts, RR: 67
Reply 9, posted (9 years 3 months 1 day 16 hours ago) and read 3191 times:

Quoting Kaddyuk (Reply 8):
I belive that the A346 anti-tailskid technology works on both landing and takeoff... but when it fails, its very easy to scrape the tail...

When it fails? Well, it's probably not that common an occurence, or? And in any case, care should be taken anyway. It's worse if computer control of the elevators should fail. The 346 is so long that the elevators move to decrease stress on the fuse from bending, and to avoid resonance vibrations.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineKaddyuk From Wallis and Futuna, joined Nov 2001, 4126 posts, RR: 26
Reply 10, posted (9 years 3 months 1 day 6 hours ago) and read 3137 times:

Quoting Starlionblue (Reply 9):
Well, it's probably not that common an occurence, or? And in any case, care should be taken anyway.

1) Nope its not a common occourance
2) Care SHOULD be taken, but sometimes it isnt and the system acts as a fail safe...

Normally two or three factors contribute towards an incident... not just one...



Whoever said "laughter is the best medicine" never had Gonorrhea
User currently offlineJetlagged From United Kingdom, joined Jan 2005, 2546 posts, RR: 24
Reply 11, posted (9 years 3 months 1 day 5 hours ago) and read 3111 times:

Quoting 2H4 (Reply 4):
If a no-flap landing requires a higher deck angle during the flare, it seems the longer aircraft would be prone to tailstrikes during landing. Just trying to find out what measures are taken in these aircraft to prevent it from happening.

There's no reason the deck angle will be any higher. Vref with no flaps will be much higher, but the angle of attack, and so the deck angle, will be much the same. If anything having leading edges devices deployed allows you to pull a higher angle of attack, so in theory you have more chance of a tailstrike in that configuration than with flaps and slats up.



The glass isn't half empty, or half full, it's twice as big as it needs to be.
User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 12, posted (9 years 3 months 20 hours ago) and read 3040 times:
AIRLINERS.NET CREW
DATABASE EDITOR

Quoting Jetlagged (Reply 11):
There's no reason the deck angle will be any higher. Vref with no flaps will be much higher, but the angle of attack, and so the deck angle, will be much the same.

Ahhhh....good point. For some reason, I was assuming identical approach speeds, in which case the deck angle would be greater. I forgot to take the increased speed (and the resulting affects on AOA) into account.

Thanks for pointing that out.


2H4





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User currently offlineAJ From Australia, joined Nov 1999, 2389 posts, RR: 24
Reply 13, posted (9 years 3 months 15 hours ago) and read 3013 times:

Quoting Jetlagged (Reply 11):
There's no reason the deck angle will be any higher.

When the flaps are at five or greater on the 767 the inboard aileron droops, designed to lower the nose attitude on approach. On a flapless approach this effect is gone leading to a shigher attitude than normal. I've done them in the simulator, they are very entertaining!

The final approach is flown below the normal clean speed (Vref30+50 instead of +80). From the FCTM "Final approach body attitude will be approximately four degrees higher than normal". Mr Boeing says to "fly the aeroplane onto the runway", no mixing of words!


User currently offlineScarebus03 From Ireland, joined Apr 2005, 304 posts, RR: 2
Reply 14, posted (9 years 2 months 4 weeks 20 hours ago) and read 2886 times:

On the A320 series to prevent tail strikes the flight control computers are programmed. But in the early days of the 321s I believe tailstrikes were quite frequent until the computers were modified. However this is a secondary system as the pilot has overall control. Also had several strikes with the 737-400 in DUB, Which is why they have a collapsable cartridge on the belly under the tail.


No faults found......................
User currently offlineSunriseValley From Canada, joined Jul 2004, 4932 posts, RR: 5
Reply 15, posted (9 years 2 months 1 week 4 days 20 hours ago) and read 2672 times:

I am not sure how widely the report on the tail strike of SQ286 at AKL was deseminated.
For those interested go to :
www2.taic.org.nz/InvDetail/03-003.aspx - 25k - 9 Jun 2005

Clearly there are software inadequacies which allowed incorrect data to be input by the pilots and not queried.
I wonder if the accident at Halifax was a result of the same set of circumstances? As I understand from the preliminary report the investigator was puzzled by the power settings used.


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