Rwy20 wrote:
You’re already climbing at your best rate of climb, maybe you can increase that slightly by going for best angle, but then what?
It shouldn’t really get to that point though should it. Not sure what terrain warning you would be getting – but I assume what you mean it says is indeed terrain, (not an obstacle/antenna for example in which case in most SEP’s you wouldn’t be getting that warning – not sure about more advanced aircraft) which by definition doesn’t move. So for argument sake – let’s say you are in a single engine plane – you should know from the Jepp charts at what altitude you ought to be by then.
If it does happen – you’ve already cleared what’s behind you – so a 180 immediate with a continuation of your climb followed by an immediate declaration of an emergency. (in which case you will hopefully get vectors if ATC is switched on enough) should at least avoid you from getting killed.
Doesn’t sound very technical but it is what i would do. Remember you are IMC – and get a warning that tells you you are about to get into CFIT. Whether that is true or a systems failure – it’s not good either way…
Rwy20 wrote:
…but then what?
If you are religious, praying might be an option. But kidding apart, for such a scenario you need a plan B beforehand. When you are already at or close to maximum rate/angle/whatever of climb and get a terrain warning, there is not a lot you can do. For commercial operations, an “escape route” has to be worked out wherever terrain clearance might be a threat. Which always has to work for the one-engine-inoperative case (or even more engines when the aircraft has more than two). We get ours by a commercial provider (APG) since some years, but before that, you could spend an hour or two over your maps an tables from the AFM, figuring out climb profiles, minimum crossing altitudes and alternative routes. If no viable plan B can be found, one does not fly there. Or only with reduced payload.
And BTW, I could not accept a departure with a 15% climb gradient for terrain or obstacle reasons with “my” little jet at work, because in case of one-engine-out we will not be able to achieve that. If it is for airspace reasons (like in Köln) that would not be a problem, because an engine failure is an emergency and in an emergency, airspace considerations are secondary,
LFHNflightstudent wrote:
f it does happen – you’ve already cleared what’s behind you – so a 180 immediate …
Again this needs to be worked out beforehand. There are enough departure routes (eg. Innsbruck, Chambery, Sion, Bolzano, Lugano, …. even seemingly harmless ones like Girona) where such a turn will take you straight into the rock face. Unless flown very tightly which in case of best angle of climb speed might lead to a stall or at least a momentary loss of altitude, making things even worse.
A very interesting discussion!
I can’t add anything to W-N’s excellent replies other than I would probably immediately do a 180. At the low speed one is likely to be going at in a SEP in that phase, say 90kt, a 180 (or, more accurately, backtracking one’s track to the airport) can be done very tightly.
However, due to icing considerations, almost every departure where terrain is an issue like that, I would be doing in VMC anyway, because if one collects ice one can forget the SID gradient 
Obviously one needs an excellent awareness of the surroundings – something way better than a GNS/GTN map. A decent tablet moving map with one’s track tail displayed would be good, even though it probably won’t display the SID.
Are there any tablet products which display a SID as a moving map? Most/all SIDs are not drawn to scale.
Last September I contemplated the following departure (PEP2A) in a DA40-180 with G1000 with moving map, terrain awareness, wind vectors, TAS indicator etc, going to Tirana (to the North-West):
Airport elevation is 2300’ with a lake to the South. There was a relatively strong northerly wind blowing. I had to make it to about FL090 before turning towards Tirana, and climb further to FL110 to clear a mountain on the border between Albania and Macedonia. I knew for sure I could do at least 600 fpm at 80 KIAS all the way to 6000’. I figured that since I had wind from the NE I could stretch my initial climb and delay my left turn towards 4DOHR. I could also stretch my southbound path by turning slowly at first inbound towards OHR.
So although the margin would not be great, I would make 6000’ before OHR. Then I would have to climb another 3000 feet over distance of 25 NM in (hopefully) headwinds.
The thing that bothered me the most was the likelihood of turbulence at FL110 and the potential difficulties to maintain altitude in mountainous area with the limited residual power,
Why we did not depart? Just as I was getting ready to start a strong rain shower moved through and my wife got worried.
Peter wrote:
Are there any tablet products which display a SID as a moving map? Most/all SIDs are not drawn to scale.
Jeppesen is currently in the process of geocoding their SID and STAR charts for mobile flight deck. But to this date very few have been updated yet. I have not come across one in real life yet.
Peter wrote:
…than I would probably immediately do a 180.
This is the only real chance you have – but you must have worked out before which direction to turn to.
I have a vivid memory of a late evening departure out of Girona about a decade ago. In an old C404 at max. takeoff mass. It was dark, but the temperature was still over 30 degrees and there was a strong westerly wind significantly increasing our ground speed. The departure was towards BGR in the east. I just looked it up – it requires a (seemingly low) climb gradient of 5,7% – but all the way up to FL80. We had a GNS 430 (or 530) with terrain display. While on the departure, the first green spots started to turn yellow, some red dots appeared, at some point almost the whole display was yellow (=less than 500ft ground clearance) and red (terrain above oneself) with a tiny little green “alley” ahead of us. Engine temperatures and oil pressures at the red lines all the time. On paper we should have been able to turn around if an engine had failed – but I am not really sure that it would have worked out in real life.
Rwy20 wrote:
Another question that has been boggling my mind for a while is, what should you do if you climb out on a SID in IMC and/or at night, and you get a terrain warning? You’re already climbing at your best rate of climb, maybe you can increase that slightly by going for best angle, but then what?
Remembers me a “justplane” video featuring Air France 340 (the old DVD, not the last one).
On takeoff from Bogota, at night, the captain (Gerard Feltzer, well known in France for being a “aviation expert” on some news channels) states to his FO “you’ll get a terrain warning, don’t pay attention”….Few seconds later, crossing 400 fts “TERRAIN TERRAIN PULL UP”….
Regarding NOR / NVO: I know what lead to NOR being taken out of service, but I can´t understand why people want to spend a million €€€ to replace it. All associated SIDs, STARs, approaches had / still have to be changed, including routings in the upper airspace. And that´s after nobody having missed anything for 18 months.
But here comes the real irony:
A0846/17 NOTAMN
Q) EDGG/QPACH/I /NBO/A /000/999/5052N00709E005
A) EDDK B) 1703020000 C) 1705212359 EST
E) DUE TO OUTAGE OF NVO DVORTAC THE FLW CHANGES TO STAR OCCUR:
AMEND NVO DVORTAC TO READ NVO INT. PSN REMAINS UNCHANGED.
Regarding the NORxP SID as an alternative: It´s only longer on paper, in real life we usually turn prop aircraft direct out of 4000ft, jets out of 6000ft.
Rwy20 wrote:
Another question that has been boggling my mind for a while is, what should you do if you climb out on a SID in IMC and/or at night, and you get a terrain warning? You’re already climbing at your best rate of climb, maybe you can increase that slightly by going for best angle, but then what?
Reminds me of every single departure I have had from 13 at Mönchengladbach EDLN has given me a terrain warning, even when passing 700ft, when there is clearly nothing for miles around – I just ignore it now
The terrain warning business is all commercially confidential and I don’t know if any GA avionics maker has ever published the algorithms.
My Garmin 496 is known to warn on the current 3D trajectory extrapolated for 120 seconds. I have tested this numerous times, including flying towards a 500ft cliff at 400ft and again at 600ft, etc. The parts which are not known, and which Garmin absolutely refuse to discuss, are the exact way the warnings are disabled when flying an IAP to a known airport. In addition, one gets warnings during e.g. climbs where the trajectory is clearly not a problem (the box seems to reduce the VS i.e. assume the climb rate will somehow decay). But the handheld TAWS products have no idea of the aircraft performance.
I have also had clearly spurious warnings on IAPs i.e. going into St Gallen. I guess there are some bugs / nonexistent obstacles.
The certified TAWS products are believed to contain more aircraft performance specific stuff, so as to more intelligently disable warnings on procedures.
It would be a brave person to ignore a TAWS warning in IMC, where terrain was known to be around. Same with TCAS actually – I always act on those, maximally aggressively.
