I think a PA28-181 will just about do FL130 on a good day so that would work.
It depends where you want to cross the alps I guess or is the question about minimum altitude no matter where you cross.
10,500 feet gets you through the Simplon pass and most trainers can do this.
In Sentimental Journey a 65 HP J-3 crossed the Rockies.
Mine (Rallye MS 892) can’t.Maximum seems 8500’
VFR? Most airplanes can do it on a fine day. The minimum altitudes to get over most passes are between 7500 and about 10’000 ft. Some are lower, such as the Brenner in Austria/Italy. At the time, I’ve crossed the Alps several times with my Cessna 150, no problem really other than on very hot days.
Rallye wrote:
Mine (Rallye MS 892) can’t.Maximum seems 8500’
It should be able to cross most passes in Switzerland and certainly the Brenner in Austria. What engine (hp) do you have? According to Wikipedia, the 892 should have 150 hp, so similar to a C172? I would say it should be able to cross the alps most of the time.
The Swiss ICAO map can be seen here:
IFR I’d say you need a reliable attainable altitude of about 17000 ft. While there are routes which have a MEA of less, (14000 ft AMSL to cross the Gotthard) with 17000 ft you will not get limited too much.
I’d say the minimum for that is about a 180hp engine. Most airplanes with 180 hp or larger can attain 15-17000 ft service ceilings. So basically any Mooneys, Cessna 182 and higher, PA28-180 and higher (Arrow) e.t.c.
I’ve done it in a Ka-6 – ok, not completely straight, but I’d regard that quite minimal…
Most airplanes can do it on a fine day. The minimum altitudes to get over most passes are between 7500 and about 10’000 ft. Some are lower, such as the Brenner in Austria/Italy. At the time, I’ve crossed the Alps several times with my Cessna 150, no problem really other than on very hot days.
Sure, but all you need is a little bit of cloud and you are screwed. Canyon flying needs 100% certainty of where you are, and quick action if you get it wrong. However to cross the Alps in most places you just need FL130+. Most of the terrain is FL110 or less, and the bits which stick out above that are obvious.
The funny thing is that most TB20 owners, Mooney owners, Bonanza owners, etc, have a fairly good idea of how high their plane will go, but most “spamcan” owners (or renters) think 5000ft is the ceiling 
And it may well be if the mysterious red lever stays fully forward. What sort of ceilings do these types actually have?
I know the max altitude of my airplane.It is a 150 hp and it will go not higher than +- 8500 ‘.I did it and at that altitude,it was nearly impossible to go higher.Maybee 9000’ max.
Minimal size? Minimal cost? Minimal weight? Minimal complexity?
One answer is a 150 HP RV-3. the procedure would be to climb at 2100 ft/min to whatever height you want, then fly toward the mountains. Service ceiling is 23,000 ft. If you want to climb a bit faster, you’ll need to compromise on simplicity and get a CS prop to achieve 2500 ft/min initial ROC.
My typical en route altitudes in a 150 HP two seater are 7500 east and 8500 west. It’s still climbing at about 500 rpm but those altitudes give good TAS with full throttle and are high enough for comfortable local terrain clearance.
A couple of times I flew my 65 HP Luscombe cross county over terrain at roughly 10,000 ft, or a few hundred less, which was the absolute ceiling. Best to head for lower ground before landing and taking off again but it had 5 hrs plus endurance on 25 USG.
C152
