PDA

View Full Version : rwy special performance


downwind
7th Jun 2003, 12:05
G'day guys,

These questions might sound stupid, but can light a/c ie <5700 Kgs, with adequate climb performance use the airline special rwy escape procedures? (not CAO 20.7.1b)

Or are these only suitable for the actual a/c to be factored for the procedure???

Also do some G/A guys use these charts in a/c ops like a B200, EMB 110, DHC 6, B58, C404 and the like even thought THEY are not certified for the a/c, but the a/c can get airborne and stay airborne?

Always asked IFR instructors there thoughts on escape routes, many have said you've just got to circle up to MSA for terrain protection within your circling area catergory and look with your own eye at the terrain within the terminal area???.

Any good thoughts on how to build a home made procedure or have an idea what to do when the sh*t hits the fan???? (loss of perf in a 20.7.4 or 20.7.2 and 20.7.1b machine, with no company resources to build or finance for data to be collected for a special procedure.

thanks,

DW.

mutt
7th Jun 2003, 14:26
We base engine failure procedures on a number of parameters, primarily a minimum bank angle and a range of speeds. Any of our aircraft that meet the requirements can use the procedure.

The trick is finding out what parameters were usedů.

Mutt.

john_tullamarine
7th Jun 2003, 19:12
DW,

Nothing silly about your question ... it is a great shame that many more pilots in low-end operations don't have the same concerns .. and a like pity that many operators ignore the problem to a greater or lesser extent ..

The simple answer to your first question is yes, provided that you take account of the segmented nature of the heavy's climb procedure and turn radius if the escape involves a turn after takeoff .....

How you go about meeting the intent of the AIP requirement for lighties with any reliability (and a half decent argument subsequently in court) is a moot point .... The original argument put forward by the Canberra chap who introduced the requirement some years ago related to the POH data ... something about meeting the 20.7.1b approach half way ...

However, as in most things, there are a few matters which you need to keep in mind ... following on from Mutt's comments (why aren't you watching the Wallabies do nasty things to your lot, Mutt ? .... present score is 14-13, 37 minutes into the first .... )

(a) for a straight ahead climb out, the heavy's segmented climb profile may, or may not, suit the climb gradient and acceleration characteristics of, say, a light twin. Be especially wary of reading the rules (eg CAO 20.7.1b as you appear to be in Australia) and presuming that the escape is predicated on the minimum airworthiness design climb requirements - often, the TOW is restricted to achieve some higher gradient necessary to achieve net flight path clearance with regard to one or more obstacles. From a practical point of view this negates your approach altogether as you will have next to no way of determining the actual figures built in to the procedure .. which is the point of Mutt's comment ...

(b) for a turning escape, the obstacle analysis is based on a design turning area (read radius of turn with some lateral buffers). If you want to follow such a procedure, you need to make good the same notional turn radius (which depends on speed and angle of bank) from the same start turn point. For the heavy, a maximum bank of 15 degrees is permitted and normally scheduled, although it is not unusual to see a procedure specify a lesser bank to achieve a desired turn radius - for instance, to allow for obstacles on the inside of the turn.

(c) circling within the declared circling area is a good idea ... provided that you have the failure above the critical obstacle (for the circling procedure declared in the letdown plate) ... which is well below the prescribed circling altitude. The problem here is that the procedure clearance above the critical obstacle in Australia varies according to aircraft category, latitude, airport met forecast status, and a few other things ... and, short of checking with the procedures designers, the figures for a particular airport are not easy to come by.

(d) Eyeballing the escape is NOT a good idea unless the airport has one or two well defined obstacles and otherwise generally benign terrain and you know where you are ... might be workable in day VMC (if you can see over the dash ?) but, otherwise ....? Generally, it is VERY difficult to eyeball two comparatively shallow gradients ie aircraft compared to the gradient needed to clear that little hill way over there that you can barely see ...


If your company doesn't have the resources to address the requirements, then perhaps management ought to keep that quiet as CASA's brief is to ensure that those requirements are met by commercial operators .. and you might find yourself out of a job. This is a common problem not helped much by CASA's lack of adequate technical engineering resources. The guys in there do their best but they are way overloaded with workload.

So, what do you do ? I guess that you are driving a cabin class twin .. the POH will have some (questionable) OEI guidance material and, in the first instance, you can match that to the declared ERSA RDS data for a straight escape ... doesn't help much for short runways with short survey distances ....

Beyond that, my friend, you are on your own .. which is why there are performance engineers .... who, unfortunately, do want to be paid for the work they do .... so, I suggest, you get your mates together and go complain to management to get the job done properly.

There is no reason why a pilot can't do the work .. but you need a few skills and adequate resources for data ...

downwind
7th Jun 2003, 20:18
John Tulla,

Good reply but do you know G/A drivers who fly b200 etc.. that use airline escape routes, ie designed by qf or dj??????

john_tullamarine
8th Jun 2003, 07:50
Yes.

I will choose not to identify them of course but, if you pose specific questions, I will do my best to speak to the question ...