-ft/m touchdown question
Thread Starter
Joined: Oct 2006
Posts: 233
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From: Manchester, UK
-ft/m touchdown question
Hi all,
Curious SLF here. Hope you don't mind me posting this. Im not sure if it's possible, but do pilots ever have an idea what there decsent rate is on touchdown (-ft/m) If so what is usually a the rate of decsent for a greaser/firm/hard landing? Im pretty sure acars records it, but im not to sure.
Im not if it has a specific name or not...
Sam
Curious SLF here. Hope you don't mind me posting this. Im not sure if it's possible, but do pilots ever have an idea what there decsent rate is on touchdown (-ft/m) If so what is usually a the rate of decsent for a greaser/firm/hard landing? Im pretty sure acars records it, but im not to sure.
Im not if it has a specific name or not...
Sam
Joined: Aug 2005
Posts: 834
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From: Estonia
By certification rules, every plane has to endure touching down at descent rate of 3 m/s at MLW and 1,8 m/s at MTOW.
Planes do not have very much more spare strength beyond that. When a Concorde touched down in Dakar at 4,2 m/s, the tail bumper wheel was crushed and the plane suffered tailstrike. The frame was repaired and flew again; but it was always heavier than the other Concordes because of the extra weight of repairs, and it was scrapped alone of all Concordes.
Planes do not have very much more spare strength beyond that. When a Concorde touched down in Dakar at 4,2 m/s, the tail bumper wheel was crushed and the plane suffered tailstrike. The frame was repaired and flew again; but it was always heavier than the other Concordes because of the extra weight of repairs, and it was scrapped alone of all Concordes.
Thread Starter
Joined: Oct 2006
Posts: 233
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From: Manchester, UK
Thread Starter
Joined: Oct 2006
Posts: 233
Likes: 0
From: Manchester, UK
Wouldn't that depend on the aircraft type though. Surely a 767 will touch down harder than 737. Now like I said, I don't know much about this so please take it with a pinch of salt. For example, if a 737 greased the landing, and was, say -20ft/m surely the 767 wouldn't be able to match that because it's alot heavier.
Joined: Aug 2005
Posts: 56
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From: New Zealand
Vert Speed on Landing
Sam,
The weight of the actual aircraft is irrelevant - any aircraft can be "greased on" with the correct combination of speed (and hence lift) and correct body angle. You are right re. the 767 - it is harder to land, but only because the bogeys are tilted the wrong way. The aircraft has a predilection for "stubbing its toes" because of this, but it is still possible to "squeak her on".
As for the certification process, I understand that the u/c must be able to withstand 1200FPM rate of descent
.
400R
The weight of the actual aircraft is irrelevant - any aircraft can be "greased on" with the correct combination of speed (and hence lift) and correct body angle. You are right re. the 767 - it is harder to land, but only because the bogeys are tilted the wrong way. The aircraft has a predilection for "stubbing its toes" because of this, but it is still possible to "squeak her on".
As for the certification process, I understand that the u/c must be able to withstand 1200FPM rate of descent
.400R
Joined: Jul 2007
Posts: 33
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From: London
Doors to automatic....
The reason the 767 gear hangs forward is to do with gear retraction. The other way wouldnt work.
Maybe there are other reasons and I am sure we will be enlightened....
All the best....
The reason the 767 gear hangs forward is to do with gear retraction. The other way wouldnt work.
Maybe there are other reasons and I am sure we will be enlightened....
All the best....
Joined: Sep 2002
Posts: 187
Likes: 2
From: Europe
A340-600:
Trouble starts at around 13 ft/s...
Unfortunately, the DMU and DFDR sometimes tell you different numbers... The sampling rate, you know...
Various MLGs have already been scrapped... Must be a bitch to land - or to detect a "hard landing" from the flight deck....
Cheers,
J.V.
Trouble starts at around 13 ft/s...
Unfortunately, the DMU and DFDR sometimes tell you different numbers... The sampling rate, you know...
Various MLGs have already been scrapped... Must be a bitch to land - or to detect a "hard landing" from the flight deck....
Cheers,
J.V.
Joined: Jan 2008
Posts: 10
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From: Indianapolis, IN USA
ACARS
You are correct, most companies set up their ACARS to monitor touchdown velocities. The last company I flew for had the ACARS set up to immediately notify Maintenance Control of a hard landing...when I say immediately I mean we got a SELCAL from Control as we taxied off the runway to tell us to write up a hard landing.
Takes the argument out of the cockpit if it was a hard landing or not.
Regards,
Greg
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Takes the argument out of the cockpit if it was a hard landing or not.
Regards,
Greg
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Joined: Aug 2005
Posts: 834
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From: Estonia
700fpm is 2.1g (according to our Flight Data Analysis system) ... and that's not OK.
Which means that after 60 cm falling at 0g, you need 55 cm to decelerate the airframe at 2,1g to stop.
How much distance does the landing gear allow for deceleration?
