Obtstacle Clearance on Departure

[punchus]

Lets assume a departure from a runway with no published SID no emer/compulsory turns published.
Two scenarios:
In the first you are cleared under radar control to take off and turn in excess of 90 degrees when ready to a down route point. (Atc responsible for terrain issues)
In the Second you are cleared as above but the radar is u/s.(procedural)
The question is from a terrain point of view does your performance keep you clear of terrain if you climb straight ahead until above MSA before commencing your turn?
If this is the case at what point do performance figures no longer clear you of obstacles. Is it MFRA or MSA?
Assume in both cases no obstacles intrude into the swept path for departures since there are no Emer/Compulsory turns.
Long Winded question I know but any info and references from the performance gurus would be much appreciated!:ok:

[411A]

On TERPS approach/departure charts, there will be a footnote for obstacle clearance, should this procedure be required, and in these cases generally, turns are not to be done below 400 feet.

[frontlefthamster]

Generally speaking, between the end of the NTOFP and MSA you are on your own unless your company has taken an interest in this and done some very clever sums... :hmm:

[john_tullamarine]

Atc responsible for terrain issues

ah ... NO !!

ATC is NOT responsible for making sure that YOU don't hit a hard bit .. they are responsible for assigning clearances which will, IF YOU COMPLY, keep you nice. However, if YOU DON'T (can't - whatever) comply, YOU are on YOUR Pat Malone ..... and this instantly is relevant if one motor fails to proceed (as RR would have it)

radar is u/s

End result is the same as for radar except that ATC can't see where you are so the tolerances and protocols are far more conservative. The same philosophy applies ... if you comply with the clearance you should be fine .. but don't try to hang YOUR terrain clearance problems on ATC's best endeavours ..


does your performance keep you clear of terrain if you climb straight ahead until above MSA before commencing your turn?

depends on the sums ... if you, or your operator, hasn't put in the hard yards over a hot computer or slide rule ... all bets are either off .. or, at the very least, you are playing Russian Roulette.

Again, if the SID, or whatever other non-failure guidance you have, is complied with by YOU, then you have a reasonable chance of a successful conclusion. However, go substantially below the REQUIRED gradients, or track incorrectly, and you might have done better going to the club and putting your change into the poker machine ...

at what point do performance figures no longer clear you of obstacles. Is it MFRA or MSA?


presuming that the OEI sums have been done correctly and appropriately then you will be on your own at the end of the calculated splays. The sums OUGHT to be done right through to wherever the en-route requirements come into play, generally MSA/LSA as applicable. I am well aware that individual operators vary in their approach and standards.

One I know used not even to bother with the terrain calcuations .. all the runway data was for nil obstacles, ie just the TOD/TOR/ASD data ... some will run only based on what terrain data is published and leave the remaining sweaty bit for the pilot .. who may well be in blissful ignorance. Often, all that saves the day is the fact that we have very few failures early in the takeoff ...

Assume in both cases no obstacles intrude into the swept path for departures since there are no Emer/Compulsory turns.

This assumption constitutes something somewhere between bravado and foolhardiness ... unless you or your ops engineers are both diligent and particular in your sums ...

[OzExpat]

Lets assume a departure from a runway with no published SID no emer/compulsory turns published.
If there is no published SID, you're on your own unless your company has crunched the numbers on all relevant obstacles in the vicinity. It could be a very big mistake to simply assume that there are no relevant obstacles along your climb path.

In any event, ATC is not responsible for your clearance from obstacles. They issue take-off and route clearances on the basis that you will avoid obstacles for yourself. This is certainly the case in many developing countries, where they might not even have an up-to-date Annex 14 survey.

Your company really should provide you with procedures for this situation so that you know where the relevant obstacles are and, more importantly, how to avoid them.

[411A]

In the USA (which uses TERPS) and, just for the sake of argument, one is operating a private aircraft (a business jet, or turbopropellor type, for example) the lack of a published departure obstacle clearance procedure from an airport which has a published instrument approach...

IF one maintains a climb rate of at least 200 feet/mile, and no turns are attempted below 400 feet (agl), terrain/obstacle clearance is assured.
Radar or no radar.

And yes, the FAA does indeed survey these things...:}