Choose the Me-262 in the QMB. Set the altitude to 10,000. Go into a steep dive. The red light comes on @630kph.

Now set the altitude to 5,000. Steep dive again. The red light comes on @900kph.

I'm stumped.

Aviar

Close Gents.

Its Mach Warning lamp.
So in effect a Max TAS light.

Source: Wings of the Luftwaffe Cap Eric Brown

hmm what i said up top. Perhaps i was right after all. Maybe like a few things in this sim it does not work right. i can not honestly say as i have never flown the 262.

In CFS-3 the red lamp located below the airspeed indicator is labled "Uberziehwarnung." It lights up when the aircraft is in a stall.

Comes on at 950 Km/hr indicated on the gauge.

Hmmm,
FB: Dive = yes. Stall = no.
CFS3: Dive = no. Stall = yes.

It is none of these. It is a pitot head overheat lamp. It warns the pilot about going too fast but exactly when it comes on depends on a few things.

The Yellow needle on the Airspeed indicator on the 262 is TAS not IAS. So 950 TAS will equate to a "Critical Mach number" i.e. Compressibility limitations.

950KMh is a 262 Dive limit speed.
Source USAF 262 Flight manual Page 13, para 15

It's interesting how many differing answers one can get from a seemingly simple question about a little red light.

Personally, none of the answers have proven anything to me, but there are a couple that have some possibilities.

Ian's post about it being a 'pitot head overheat lamp' is interesting but he needs to elaborate at least a little more. For instance, just what is a 'pitot head', why and how does it overheat and what are the "few things' that determine when the light comes on.

IvanK's statement that it is a 'Mach Warning lamp' sounds definitive, but I have serious doubts about it. If it is warning about Mach speed, why then does it come on at different speeds (630kph - 900kph)? BTW, these speed readings were taken from the speed bar. His last post hurts his case even more, as I had already posted earlier about the different speeds at which the light comes on.

The other posts are all ruled out for obvious reasons. Come on people, do I have to look this up myself? That goes against all forum traditions. We all know it's easier to ask other people to do our dirty work...

Aviar

It is a pitot head overheat warning lamp and you're just being lazy

OK, OK ...

A pitot head is the spiky thing (technical term!) that measures airspeed. Too fast plane > too fast spinning pitot > overheat > red lamp. Therefore the red lamp warns that you're going too fast.

As for different times - a brief overspeed wont set the lamp off immediately, but a prolonged dive (etc) will.