In the absence of any data from the accident itself, many find that speculation is unwelcome. In this incident, there are points however that I would like to address in the most general sense. I find particularly disturbing, the attitude of some, that instrument flying is somehow easy and doesn’t deserve careful and meticulous planning, proper briefing, and accurate flying backed up by close monitoring. Those protagonists are quite simply wrong.
There is nothing intrinsically dangerous about Zurich/Kloten or its many instrument approaches and their variations. There are however a number of local factors which cannot be ignored by the professional pilot. Not the least of these is the surrounding terrain. The obvious proximity of mountainous areas presents its own problems, which manifest themselves as katabatic, and valley winds that give notorious tail components onto the main southerly runways. This is often exacerbated by the entertaining speed requirements of Zurich ATC.
Furthermore, radar vectoring, particularly at busy times can lead the unwary into close proximity with the terrain if followed for extended periods. You should always ask yourself ‘How long am I prepared to accept this heading?’, ‘If I lose radio, how shall I manoeuvre to avoid the hills?’. You might also consider the fact that holding for up to 45 minutes is not uncommon last thing at night as the noise ban takes effect. Take the fuel rather than wish you had it later. The last thing you want is a low fuel state distracting you from the careful planning required.
More importantly, there are a number of little ‘hillocks’ surrounding the airport that need to be considered in your briefings and planning for all approaches and departures from Zurich. Staring with the southerly approaches, there are two outcrops, which come close to the approach surface. One is at about 8d and for an on-slope aircraft gives only about 1400’ safe clearance, and the other at 4d which comes even closer. ILS approaches to these runways need to be conducted in such a way as to avoid infringing the GPWS envelopes for mode 4 & 5 warnings. Remember also that EGPWS will give alerts 40 – 60 secs before projected impact with solid reds. Early configuration and careful attention to energy profile management will alleviate these potential pitfalls, and in my opinion are best avoided by a continuous descent profile, remaining on the 300 ft/nm slope from as soon as possible after leaving the holding fix. These are important criteria that require careful briefing, especially with new or inexperienced colleagues.
The procedural and non-precision approaches are even more exacting than the ILS because of the lack of radio slope guidance and wider statistical scatter of ‘on-track’ approaches. A non-precision approach is a means of securing a stabilised visual approach from an IFR transition. The VOR onto RWY 28 strikes me particularly as having one or two points that require specific attention. Three or four minutes extra in the planning and briefing would not be wasted in my opinion before commencing this approach. Firstly, the approach path is very short, scarcely 20nm from the ZUE beacon to touch down. Adherence to track and vertical profile is essential to ensure safe separation from the surrounding high terrain and ‘hillocks’, and in my opinion the aircraft should be configured at least with gear down and approach flap setting from the ZUE beacon. Configuration changes and attendant trim changes will not assist accurate flying after this point. The final turn onto the inbound course is particularly challenging, since it is just 7nm from touchdown, less than 1500’ above the local terrain, and requires the aircraft to be on track and in the final landing configuration as you roll out. With the strong westerlies that sometimes predicate this approach, such parameters are not easy to achieve. Remember also that this is a VOR approach, the beam bar is not as sensitive as an ILS localiser, and will not receive the enhancement that many modern flight systems apply to localiser deviation. The rate of closure may be slower than you might expect, and an early or rapid turn onto FAC would leave the aircraft North of track and outside the parameters to commence the final descent. Turning any earlier than the lead radial would put you dangerously close to the local terrain and in no circumstances should the approach be continued.
It is important to consider also that during the winter months, altimeter temperature error correction MUST BE APPLIED to the heights given on the plate. The barometric altimeter will overread by 40ft/1000’ above the airfield reference (HAT for most purposes) for every 10° below ISA. On the night in question, with a temperature of 0° at Kloten, this would have meant adding 4.8% to all of the heights on the approach. Remember there is no radio slope guidance, and therefore the barometric altimeter is the only source of vertical profile indication.
The missed approach presents its own problems for terrain clearance and for that matter departures too off RWY 28. Without going into too much detail, an aircraft in the engine out case is likely to have a genuine GPWS warning even at scheduled performance if even slightly off the advertised path, the KLO 255R. See what your aircraft would do in this case.
This accident is especially tragic since it happened to a local operator probably well used to this approach. You must ask yourself how you might perform the approach in your aircraft with your SOP’s. What would be the effect of icing? On some aeroplanes, engine antice requires increased engine power, affecting your ability to control energy. Some companies require a hand over of control during the final phase of the approach, some companies advocate an immediate descent to MDA at the final step down fix. For my part I would fly it fully configured and as a 3.7°/370 nm profile so as to be at the MDA of 2390’, 3.25 miles from touchdown. That way the aircraft is in a stable landing configuration at you enter the visual segment.
End of rant. If you take anything away from this, all I ask is that you talk about this over a pint in the pub, or in the crew bus, but whatever you do don’t leave it ‘til your just leaving the hold.
God rest the victims of this accident. Safe flying.
PS: I get the impression that some people think I'm having a pop at the Crossair crew. Nothing could be further from the truth. You have a duty to your passengers though to examine the issues raised to see if there's any of your skills that you might think about improving in the light of these tragic events. If you, like me, try to learn something new every day then I hope my post has helped you to think. If you know everything already, perhaps you might post your details so that I can avoid flying with you in the future.
[ 28 November 2001: Message edited by: Capt H Peacock ]