This is a valuable thread enabling opportunity to think about safety issues and learn from them; thanks to all of the contributors.
TowerDog no criticism of your view on mechanical failure; although unlikely, this is not totally dismissed particularly in an operation where the tyres, brakes / gear might be at the top end of their performance spec – high energy (speed altitude), tyre speed/temp.
Re” Landing long at high speed would of course trigger a no-fault go-around. - Surely the Iberia crews are trained to think that way.”
Yes, but such assumptions are often found to be inaccurate due to the limitations of human performance; we (all of us) forget, we are distracted, we press-on because we ’think’ that it safe or not knowing the risk, or we do not know how close to the edge of a safe operation the particular landing is.
MoodyBlue, re PAPI not aligned with ILS GS. I agree with your deduction. Not forgetting that the ILS GS is a reflected beam from the ground some distance in front of the aerial (at 3 deg down then up), there appears to be a discrepancy which is not identified in the charts – thus an opportunity for error.
One such error is to duck under the ILS GS and follow the PAPI visual slope; this could be a particular hazard in long body aircraft (large eye/wheel height, long eye/wheel dist) where the resultant TCH could be extremely low. Comparing the A340-600 with a smaller aircraft aiming for TCH 50ft +/- 10ft, the A340 following the same visual path may only have 20ft +/- 10ft wheel clearance. [eye-wheel ht ~ 18ft, + attitude correction 12ft (6deg @ 120ft eye wheel dist – from Airbus ebriefing 2006)]. A further consideration may be that apart from the risk of the manoeuvre, a duck under at higher GS (higher energy/inertia) might result in an overshoot of the desired visual path giving even less TCH clearance. Then consider the lack of a paved undershoot area before the threshold (see pics #114).
polea, “the plane landed after the first 1/3 of the runway (pilot error) … ”. This statement follows the old view of error – pilot error.
Consider an IFR operation with the planned touchdown aim-point based on the ILS origin, then a small change in the tailwind or the ‘standard’ error in reporting the wind (see link from #108), could cause the aircraft to float down the runway, even further if it were ‘over the first hump’ beyond the touchdown markings. Alternatively, consider the possibility of a visual illusion with the up-sloping runway or a relatively narrow runway for its extra length, or poor light/visibility (dusk?), any of these factors makes the landing a demanding task in a large aircraft. Then consider any differences between management operational assumptions vs what the crew assumed; what landing distance is assumed; full length, 2610m, or even less (it would be nice to establish what value operators’ use in their planning charts or perf computers – cf 737 Midway accident - data in computer).
Thus the ‘long landing’ could be within the normal distribution of touchdown position when compared with a landing on a non limiting runway. What we don’t know are the assumptions in the operation, I hope the crew knew.
Considering the plans for a new airport, then improvements at UIO appear unlikely and with financial constraint even runway maintenance cleaning/removal of rubber deposits may be overlooked. Thus the operator / crew will have to accommodate any additional risk during landing. Add to the above a wet runway which had less friction than normal – greater depth of water, or residual dust in the runway pores (there doesn’t have to be an active volcano), blocked grooves (is the runway grooved?), and increasing rubber deposits, then the risk of an overrun increases.
Crews may rarely encounter truly limiting runways, thus they acquire and present a perception of apparent safety (“737 land safely so why can everyone else”). Whereas landing performance provides a safety margin for normal flying tolerances, the margin cannot accommodate a combination of extremes or any false assumptions carried over from less demanding operations.
A routine, ‘normal’ landing might consume 50% of the safety margin due to deviations from the ideal in approach speed, TCH, flare time, touchdown position, spoiler/rev deployment, and use of brakes. The crew’s perception, particularly on a non limiting runway could be of a large residual safety margin based on the runway remaining; what they may fail to appreciate is where they where expected to stop by the certification and operational assumptions. Thus it is possible to form a biased view of the margins of safety based on normal operations, …. but UIO is not normal.
JAR-OPS performance is based on a ‘standard’ wet runway (only found in certification?), in practice there is a range of reducing levels of friction between wet and some magic changeover point of flooded/contaminated – what the crew do not know is how slippery a wet runway is (excluding ‘slippery when wet’ which is separate, but important additional risk). So for a crew who for good reason conduct a difficult landing at UIO as perhaps they have done before, suddenly find that that the margin of safety rapidly disappears and alternative action is required – more reverse or more brakes – just at the point where the runway is wet, slippery, and contaminated with rubber!
Some research suggests that it is necessary to increase existing safety factor from 1.92 up to 2.2/2.4 on wet runway in order to maintain the same level of safety on a dry runway.
For those who use a
w -
b analysis it might be interesting to take a speculative view of this scenario and ‘pencil-in’ opportunities for error and thus preventative measures, e.g.
why at UIO aircraft should not duck under:
because an unstable approach may offset any gain in landing distance, possible reduced TCH, no undershoot.
why max braking should be considered:
because the point of touchdown may vary more than normal, prevalence of tailwind landings, potentially slippery runway (wet and dry - dusty?), non standard overrun area.
This proactive assessment could be the basis of a special briefing or SOP, which of course should include a GA if the TD position appears to be long (specify a fixed point on the runway).
Refs:
Runway Slipperiness Research.
Safety Factor on Wet Concrete Runway.