About ten minutes after departure, Autopilot is turned on and Im following my route. I get a sound which is like a warning sound! There is no indication on the panel or displays that there is something wrong. Weird!?! What am I doing wrong or is this a bug?

Sounds like a pressurisation issue - what do the pressurisation gauges show at the time? Thanks Chris.

Sounds like a pressurisation issue - what do the pressurisation gauges show at the time? Thanks Chris.

I will take a look.

The warning will be on the first officers caution panel. It will be because your packs are not on or you have not set the pressurisation panel.Need to dial in your planned cruise altitude and set to auto. On the gauge the inside needle is the atmospheric pressure altitude inside the aircraft and the outside needle is the pressure differential. Dan.

If you're getting what sounds like a gear horn, the altitude in the cabin is too high.

There is a button on the overhead panel that will silence the warning sound, go look for it. But it won't take away the problem of course.

This is what happens when it is ignored http://en.wikipedia.org/wiki/Helios_Airways_Flight_522

Probably when you hear of that warning sound, switch your cam to FO side and you must be seeing caution light on writing next to it 'OVERHEAD'. I think after takeoff or just before the takeoff you didn't turn on the packs.

If it is the cabin altitude warning horn there is no light that goes along with it in the PMDG 737. The master caution will not illuminate for cabin altitude. New 737s have lights on the main instrument panel that will indicate whether it is a take off configuration warning or cabin altitude warning but that is not modeled on the simulation.

The only light with the cabin warning is just above the pressurization panel that says "AUTO FAIL" , assuming you don't have it in manual like in the Helios flight.

I tried depressurization today, just few seconds after turning off packs I had the warning, and the AUTO FAIL light. I'm not sure that few seconds, with the outflow near to the closed position, caused in few seconds a full depress.Switched packs on again and re-pressurized aircraft in manual mode untill auto was back online.Not sure that it is normal that AUTO FAIL comes on when flying with packs off.I'm going to check my manuals. Found on AMM:

These things cause the autofail function:

• Power loss
• Cabin altitude rate of change is too high (>2,000 slfpm)
• Cabin altitude is too high (>15,800 ft)
• Wiring failures
• Outflow valve component failures
• CPC failures
• Cabin differential pressure is too high (>8.75 psi).

With these conditions the warning horn starts before the light (10000ft cabin altitude, assuming that press control is on AUTO or the outflow valve is on the closed position), and probably, if I pilot hear it, will solve the problem before the light.

The only light with the cabin warning is just above the pressurization panel that says "AUTO FAIL" , assuming you don't have it in manual like in the Helios flight.

I just want to be clear about the systems stuff. The AUTO FAIL light won't necessarily accompany the cabin altitude warning. It is possible to get the warning sound with no lights. It has happened where the only warning the crew received was the cabin altitude warning when they failed to turn the pack on.

I just want to be clear about the systems stuff. The AUTO FAIL light won't necessarily accompany the cabin altitude warning. It is possible to get the warning sound with no lights. It has happened where the only warning the crew received was the cabin altitude warning when they failed to turn the pack on.

As I wrote the 2 annunciations have different logic.If panel is left in AUTO position, and packs are off, the outflow valve will be commanded fully closed trying to maintain pressure. Controller will then not recognize more than 2000ft/min that triggers the AUTO FAIL, but, the cabin pressure will decrease untill reaching 10000 feets, at this moment the pressurization warning sound will play. If packs are restored the alarm will cease, if not, reaching 15800ft of cabin pressure, the AUTOFAIL will come on.

If you're getting what sounds like a gear horn, the altitude in the cabin is too high.

Shouldn't it be the same as the takeoff config warning (ie. an intermittent tone rather than a constant tone like for the gear warn).

Shouldn't it be the same as the takeoff config warning (ie. an intermittent tone rather than a constant tone like for the gear warn).

No sir. Gear horn sound.