TAWS usage in IF as only sepperation to Mountains

[DopplerPilot]

Do you think flying in other countries make it legal?

Using a GPS for IF approach, not legal in some countries...

Radar descending into mountanious terrain, a no no?

[IO540]

What is an "IF approach"?

[421C]

There aren't any circumstances I am aware of where TAWS lets you descend with less terrain clearance than that provided by published routes and procedures, or permitted under ATC radar vectoring, or under ATC procedural safe altitudes, or under the off-route 1000' terrain clearance rules.

TAWS is warning system to reduce the risk of flying into terrain if something goes wrong with the normal IFR practices. It's not a navigation system.

brgds
421C

[Droopystop]

Even EGPWS is not to be used as NAV aid (which is basically what I think you are eluding to?). Descending below MESA in mountainous terrain without an instrument approach is asking for trouble.

[scooter boy]

421C and Droopystop are right.
I don't want to sound over dramatic but IFR in IMC in mountainous terrain outside of an airway or published approach procedure seems a pretty good recipe for CFIT.

Crossing the Alps for example, I would choose to be in an airway in class A controlled airspace preferably above the weather but even if in IMC weather I would know I wasn't going to hit the granite.

I have TAWS and use it as a backup, I would definitely have it switched on while flying through the mountains at night even if in an airway, just in case the engine quit, but would be very unhappy picking my way through the passes in weather using GPS and TAWS.

SB

PS: IO540, I think IF approach means instrument approach.

[englishal]

I don't want to sound over dramatic but IFR in IMC in mountainous terrain outside of an airway or published approach procedure seems a pretty good recipe for CFIT.

Only if you are below the MOCA.

[mm_flynn]

I suspect DopplerPilot is making a veiled reference to some antics he has seen from foreign pilots in SA.


SB - In general it is not possible to be in class A over the Alps [/pedant mode off]. The general principle of wanting to be on a published airway above the MEA is one with which I would definitely agree.

[IO540]

When IFR, ATC probably won't let you cross the Alps (or anything else) if you are below their MVA.

When VFR, they couldn't care less And if you have to fly below CAS (Class C usually), it gets "quite" close especially on the routes down from Switzerland...

Anyway, I can't see how TAWS / EGPWS would be of use in terrain avoidance. You don't get a very good picture from it, and the database can be somewhat suspect. If one is going to be a real cowboy, one will run a copy of FSX or X-Plane in the cockpit, with the ex-NASA SRTM DVD terrain set, and feed the NMEA GPS data stream into the computer running it I should think that, in Africa, anything goes. Especially in SA where men are still real men.