http://www.cad.gov.hk/reports/main1.pdf
The final report on the Ci MD11 crash in HK lends some insight into some of the MD11's characteristics while landing in difficult weather.
In that accident it was decided that a possible loss of headwind component along with the ATS powering engines down to idle by 35feet RA (per design) resulted in the RMLG contacting ground at 18 feet per second. This was beyond its design limit of 12 feet per second and caused the gear to shear off outwards resulting in right wing failure due to number 3 ground contact and subsequent aircraft inversion and resultant fire. It is noted that the left wing still had sufficient lift and contributed to the inversion of the aircraft. It was recommended that the MD11 not be flown on A/T while descending on final in possible windshear situations. And that perhaps the timely addition of power seconds before the main gear contacted could perhaps have kept the rate of descent within design limit and thus avoided this incident. However this passage is interesting to note:
"The simulator FCC was initially loaded
with the standard – 907 model FCC software used in the accident
aircraft, and a series of approaches were flown by a number of
Boeing and China Airline pilots, and by a HKCAD accident
investigator type-qualified on the MD11. During these approaches,
ability to flare the simulator below 50 ft using the technique
recommended in the China Airlines Operations Manual and achieve
a normal touchdown at a low rate of descent proved unsuccessful on
the majority of approaches flown; if power was manually applied late
in the flare, the rate of descent could be reduced but was still high at
touchdown. By comparison, and although the crosswind exceeded
the published limits for autolanding, successful autolandings could
be completed but involved an exaggerated pitch up to nearly 10°,
well beyond that which would normally be expected.
The China Airline’s co-pilot involved in the accident observed the
latter simulations. He subjectively assessed the simulated
conditions as realistic, except that he recalled the turbulence level
below about 150 ft as being greater on the accident approach than
even the highest level which could be set in the simulator.."
Leaving me to believe that the MD11 really is a handful in gusty crosswind landings. Could we call it "unsafe" even in such a situation given this latest Fedex crash and the Ci crash. The 1997 Fedex crash was in good weather but it was bounced during landing and improperly restrained? It takes way better then average ability to land this big bird safely in high winds or a bounce it would appear.
It was also interesting to note that the Captain left HK within days of the incident without reference to the local authorities or China Airlines and refused to be interviewed regarding this incident outside of later sending a prepared statement and answering some questions via fax. I understand he gave up flying after that. But in fact he seems to have done most things right that fateful night. Other then in hindsight he would've done better to have diverted in view of the knowledge of the crosswind gusting to 35 knots plus. The only mistake he seemed to have made in the actual landing is that he should have been on manual throttle control in the landing phase in order to be able to apply thrust during the fateful last few seconds. Maybe he really should've been flying another plane altogether that night? Perhaps a 777? I am just saying that the MD11 seems not the ideal aircraft in that kind of weather to land in, being so exacting in its requirements.
The latest Fedex accident really brought home how lucky the crew and passengers of the Ci HK incident were in surviving with only 3 deaths out of over 300 onboard.
The report gives these insights regarding the LSAS :
"
1.6.5. Longitudinal Stability Augmentation System
The aircraft is equipped with a Longitudinal Stability Augmentation
System (LSAS) which provides pitch attitude hold and limiting pitch
rate damping, automatic pitch trim, speed protection and stall
protection. LSAS is not provided when the autopilot is engaged.
Below 100 ft RA, and transparent to the pilot, LSAS is progressively
removed from the pitch control system.
LSAS holds the aircraft’s current pitch attitude if there is no force on
the control column and the bank angle is less than 30º. If the pilot
manually changes pitch attitude and then removes the control
column force, the aircraft will hold the new pitch attitude.
LSAS holds pitch attitude by deflecting the elevators up to 5º, and
the stabiliser is then automatically adjusted to relieve sustained
elevator deflection and maintain a full 5º of elevator authority.
LSAS also limits pitch attitude to less than 10º of aircraft nose down
(AND) or 30º of aircraft nose up (ANU). Below 15,000 ft, if there
is more than approximately two pounds (lb) (0.9 kilogram) of force "
This report had these comments in regards to the Fedex crash in Newark in 1997:
"1.18.8. MD11 landing accident – Newark International Airport, USA
On 31 July 1997, a MD11 freighter aircraft was involved in an
accident with similar consequences when landing at Newark
International Airport, New Jersey, USA. In that accident, which
occurred in good weather conditions, the aircraft also suffered
structural failure of the RMLG and right wing rear spar, and came to
rest inverted.
The US National Transportation Safety Board (NTSB) investigation
concluded that the probable cause of the accident was overcontrol of
the aircraft during landing. This involved elevator deflections
varying from 26º ANU to 18º AND, and resulted in an initial
touchdown that become airborne again followed by a heavy second
touchdown during which the structural failure occurred. The
second touchdown was in a 9.5º right wing down attitude with a rate
of descent at the RMLG calculated as 13.5 feet per second. "
This may help us understand this latest MD11 incident.