Emergency descent in high terrain

[keith smith]

I am sure somebody must have thought about it, but is there a risk of running out of anywhere to go during a descent forced by decompression when travelling over high terrain (e.g.Himalayas or European Alps)?
. Oxygen will only last for a limited time, and you have to reach10K ft in order to preserve life of elderly and infirm.
Best route may not be straight ahead, but how do you decide in a hurry? EGPWS, with suitable software might help.:)

[keith smith]

I have just found out that this was discussed lasy year. Still I did float the idea of using EGPWS

[Pilot Pete]

Best route may not be straight ahead, but how do you decide in a hurry? It's called situational awareness, which good pilots constantly update as they fly along. Oxygen escape charts for mountainous terrain also play a part....

EGPWS, with suitable software might help. There is no such thing as EGPWS without suitable software, so I don't understand that part of your statement, but you would be a fool to use EGPWS as a planning tool to get yourself down to FL100 or below in mountainous terrain.

PP

[keith smith]

Pilot Pete, The existing software for EGPWS doesn't do any flight planning, it merely warns you when you are likely to hit something if you continue doing whatever youa realready doing.
The advantage of flexible escape instructions based onpresent postion and terrain data is that it can plan instantly., wherever you are.

[SNS3Guppy]

I made a flight with a pilot who was deeply impressed with his EGPWS and terrain map displays. He too insisted that it would be an excellent escape tool. We had an empty leg in a location I knew, so I flew him to a point below the terrain in a valley with rising terrain, and asked him to identify his escape. He picked it out, and I flew him to the canyon entrance where he thought the drainage and lowering terrain would exist. Turns out it would have killed him. He changed his thoughts on the subject.

Hopefully you will have someone do the same for you before you attempt to predicate your terrain clearance on a moving map and EGPWS.

Situational awareness is the key.

Arriving at an altitude above 10,000 does not spell death for everyone on board.

[Pilot Pete]

The existing software for EGPWS doesn't do any flight planning, it merely warns you when you are likely to hit something if you continue doing whatever youa realready doing. Never said it did any planning....and if you are going to use the info for your emergency descent then let me know who you work for and I will avoid flying with your airline.

As has been pointed out to you twice, it is all about SA. With a chart out it is easy to decide which way you are going to turn (if at all) and what level you are going to descend to in order to stay above the highest MSA in your immediate vacinity, and then to monitor your track to an area of lower MSA, knowing when it is safe to descend further. Of course, with your up to date SA you would have already checked and have to hand your Oxygen Escape Chart for the area, tuned suitable navaids to give raw data fix position if needed and have checked the winds and surface temperature and applied suitable add-ons to the area MSA to avoid having to respond to your EGPWS.......now you would have done all that wouldn't you?;)

PP

[DC2 slf]

<snip>

Arriving at an altitude above 10,000 does not spell death for everyone on board.

Quite a few tourists visit places above 10,000 without oxygen!

[BelArgUSA]

People in La Paz, Bolivia, live at 14,000 feet MSL... Any airplane operating to that airport requires a special 14,000 P-ALT optional T/O and LNDG limitation, as most Part 25 airplanes are normally limited to 10,000 P-ALT. Special cabin oxygen system re-calibration to 15,000 P-ALT also required for passenger masks, since, with a somewhat "low QNH", your cabin masks would fall due to the aneroid switch which triggers the PSUs to release the masks at 14,000 P-ALT (plus/minus 500 ft). A separate circuit breaker is required to silence the cabin altitude warning horn which would normally sound at/above 10,000 P-ALT.
xxx
At times, PanAm operated B-720Bs to/from La Paz. The PanAm GOM required the cockpit crew to use their O2 masks continuously for 15 minutes prior takeoff, until cabin altitude was returned to below 10,000 P-ALT, and for approach/landing. A few 720s in the fleet had the special "high altiude" operations kit. The LAB Bolivian crews do not have such a rule... I guess they have turbocharged lungs...
xxx
After the Himalayas, you can find the next highest minimum enroute levels (in the order of FL 250/260) to be between Mendoza (Argentina) and Santiago (Chile), near Cerro Aconcagua (6,965 meters high)... A regular emergency descent for pressurization loss is basically impossible in that area. The only option is a "180º turn" towards Mendoza/Cordoba on the Argentina side, and towards the Pacific Ocean on the Chilean side. DME from Mendoza or Santiago can be used to know which way to go, turn, or continue to descent.
xxx
If VMC, you might be able to negotiate some mountain passes at about FL 160/170. If you ever fly that route with good visibility, the VMC descent into Santiago is quite scenic. Recommend you to take your camera, it is worth it.
xxx
:)
Happy contrails

[BuzzBox]

We carry Enroute Diversion Guides for those routes where terrain is likely to be a problem in the event of an engine failure or depressurisation. The guide depicts the minimum altitude to be flown for each segment of the route and also shows any applicable escape routes.

Minimum dispatch oxygen pressures (for crew and pax systems) have been calculated for the routes we fly, and cater for a depressurisation at the worst place enroute. Provided we dispatch with at least the minimum oxygen pressure for the route, there will be enough oxygen available for the crew and pax, even if the terrain dictates a minimum altitude greater than 10,000ft for some time after the depressurisation.

The EGPWS is designed as a warning system, not as a tool for planning an escape route. I'm sure most would agree that to use it as a planning tool would be pure folly.

[chornedsnorkack]

The Andes...
People in La Paz, Bolivia, live at 14,000 feet MSL... Any airplane operating to that airport requires a special 14,000 P-ALT optional T/O and LNDG limitation, as most Part 25 airplanes are normally limited to 10,000 P-ALT. Special cabin oxygen system re-calibration to 15,000 P-ALT also required for passenger masks, since, with a somewhat "low QNH", your cabin masks would fall due to the aneroid switch which triggers the PSUs to release the masks at 14,000 P-ALT (plus/minus 500 ft). A separate circuit breaker is required to silence the cabin altitude warning horn which would normally sound at/above 10,000 P-ALT.
And the longest runway in the world, that of Bangda, is about 300 m higher than El Alto. Gonggar, however, is lower than El Alto.

xxx
At times, PanAm operated B-720Bs to/from La Paz. The PanAm GOM required the cockpit crew to use their O2 masks continuously for 15 minutes prior takeoff, until cabin altitude was returned to below 10,000 P-ALT, and for approach/landing. A few 720s in the fleet had the special "high altiude" operations kit. The LAB Bolivian crews do not have such a rule... I guess they have turbocharged lungs...

People live and do heavy physical and safety-critical work well above 14 000 feet. But they usually spend some days, or more, reaching those altitudes.

In Andes, there was an example to the effect that people should not live above 18 000 feet. A mine which is located at 19 000 feet - mining is heavy physical, safety-critical work. The miners used to sleep in a camp at 17 500 feet, and climb to the mine daily. It was tried to make a camp at 18 500 feet. But then the miners found that they could not sleep properly, and felt worse. So the miners returned to sleeping at 17 500 feet and climbing 1500 feet every morning.

[Pace]

Are you talking FAA or JAA ? FAA Dicatate 12500 feet for pilots with 14000 feet for up to 30 minutes and passengers 15000.

15000 would clear most of the Alps other than a few peaks and there is always the option of staying on oxygen until clear of high terrain instead of a far greater risk of descending blind into high terrain.

Pace

[scotty.aka.dan]

Theres a document on smartcockpit but I think you would need to recall the information from memory for it to be really useful as the last thing you would want to do during an emergency decent would be reading this document! SmartCockpit - Airline training guides, Aviation, Operations, Safety (http://www.smartcockpit.com/pdf/swissknife/flight_case/0003/)