Author Topic: FedEx 1420 - tailstrike at DEN  (Read 11964 times)

Offline Eric M

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FedEx 1420 - tailstrike at DEN
« on: January 25, 2013, 03:14:10 PM »
Okay, so it's not THAT interesting, but a FedEx MD-11 experienced a tailstrike while landing at DEN this morning. Edited down for relevance.

AVHerald.com reported on it here, including photos: http://www.avherald.com/h?article=45cb7632&opt=0



Offline datainmotion

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Re: FedEx 1420 - tailstrike at DEN
« Reply #1 on: January 28, 2013, 10:39:50 PM »
Eric,

I'm assuming you had to clean up some of the audio quite a bit for us to hear Ops 7 on the TWR freq? It seems like those 25W mobiles in their trucks are almost never readable from 13 miles away.
Thanks for sharing it.

Mike

Offline Eric M

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Re: FedEx 1420 - tailstrike at DEN
« Reply #2 on: January 29, 2013, 11:06:31 PM »
Hi Mike - no, I'm pleased to tell you those were straight off the archive. I edited for silence and unrelated comms only. Must've been a nice clear morning with not a lot of other interference.

Offline 777-200LR

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Re: FedEx 1420 - tailstrike at DEN
« Reply #3 on: February 22, 2013, 11:13:28 PM »
Tailstrikes are probably more common at high altitude airports.

757-rules

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Re: FedEx 1420 - tailstrike at DEN
« Reply #4 on: February 23, 2013, 05:15:59 AM »
Tailstrikes are probably more common at high altitude airports.

Why would that be? Elevated runways have nothing to do with tailstrikes, see this page for example: http://www.avherald.com/h?search_term=tailstrike&opt=0&dosearch=1&search.x=0&search.y=0

Most airports are at normal altitude... (But rather than flaps at 10 or 15 they choose 5 and lots of (pitch)trim setting....)
« Last Edit: February 23, 2013, 05:17:56 AM by 757-rules »

Offline 777-200LR

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Re: FedEx 1420 - tailstrike at DEN
« Reply #5 on: February 24, 2013, 12:56:30 AM »
Tail strikes are more likely to occur at high (density) altitude airports for several reasons —  all related to density altitude.  The same flare that works well at a sea level field like JFK can give you a tail strike at DEN.  For the MD-11 Fed Ex that was likely loaded with cargo, the Vapp will usually approach Vls.  Retarding the throttle on touchdown is done much less at high altitude airports than at sea level fields.  You never really know how much the FMS software fully takes into account the high density altitude of the airport when computing Vref.

Because of the higher landing speeds and reduced effectiveness of the flare to reduce the sink rate at high altitude airports, the oleo-pneumatic shocks on the main gear will compress more on touch down at DEN than a sea level landing (assume all other factors equal).  This Fed Ex MD-11 reported a "hard landing" which likely compressed their main shocks to near their full stop.  That same landing speed and flare at sea level airport would have cleared their tail because it would have arrested the high sink rate.

Whenever flying into or out of a high altitude airport, it is best to get your sink rate under control earlier than normal and keep your speed up.

Choosing a higher flaps setting on takeoff will actually make a tail strike less likely because it gives you added pitch though clean-up is bit of a hustle.  But on landing, pilots use the same landing flaps as at sea level airports (max), which means they will have less tail clearance than that same landing flare done at a sea level airport (again, all other things equal - i.e. plane weight, headwinds, CG, etc.).

To reduce tail strikes, Fed Ex should consider loading their planes with their CG moved forward, so after fuel burn they have less alpha on the flare.
« Last Edit: February 24, 2013, 10:57:46 PM by 777-200LR »

Offline Robert Larson

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Re: FedEx 1420 - tailstrike at DEN
« Reply #6 on: February 24, 2013, 08:16:05 AM »
essentially there's less air at higher altitudes to hold the plane up (density altitude) so the plane has to maintain a higher angle of attack to generate the same amount of lift at a lower altitude at a given approach speed.
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Offline datainmotion

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Re: FedEx 1420 - tailstrike at DEN
« Reply #7 on: February 25, 2013, 02:57:23 AM »
FWIW - when I worked at the FX DEN Ramp, MD-11s were a rarity. So with that said, and if still rare, MD-11 pilots may not be as "well-versed" with DEN landing and t/o procedures.

Offline 777-200LR

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Re: FedEx 1420 - tailstrike at DEN
« Reply #8 on: March 02, 2013, 03:42:26 AM »
FWIW - when I worked at the FX DEN Ramp, MD-11s were a rarity. So with that said, and if still rare, MD-11 pilots may not be as "well-versed" with DEN landing and t/o procedures.

datainmotion — Yes, I too was wondering if this crew (and MD-11's) were regulars at KDEN.   Your personal knowledge leads me to believe that this crew was caught off guard by the subtle changes they needed to make to execute their approach, landing, and flare at a high-altitude airport.  Plus, MD-11's and its sister ship DC-10 were known to be squirrely critters when it came to elevator input on landing flares.  The bounce, roll, and hull loss of 2 FedEx DC-11's — one at Newark and the other at Narita in Japan — tell me the 11's are not exactly the most forgiving AC when it comes to dialing in the flare.