Level 1, 2 and 3 are not described in FCOM. The expression "Level" originates from a group of instructors at ATR who wanted to simplify the wording from "Probe heating & windshield heating", etc, to something easier to understand. However, since Level 1, 2 and 3 are not printed on the panels, this practice is not official.

Sure, but you will not be able to understand it. An FMS doesn't work in a flat world.

@@FlywithMagnar I can demonstrate how the. Fms works on flat earth! But first show me how you use one, then after I will sho lw you how it works on flat earth!

The user manual has more than 500 pages, but for a starter, the main means of navigation is GPS, GLONASS or Galileo. They consist of satellites orbiting Earth. This is not possible with a flat Earth. (This answer has been edited. I lost the internet connection.)

@@FlywithMagnar Ok)

The exhaust mode pushbutton controls the extract fan. If the extract fan stops, the avionics might overheat. Therefore, if someone switches off the pushbutton while the aircraft is parked on the ground, the horn will sound. And if I remember correctly, the horn will also sound if the fan fails while the aircraft is parked on the ground. Finally, the horn will activate 30 seconds after the emergency beacon is activated while the aircraft is on the ground and is powered.

@@FlywithMagnar Thank you for the information : )

Hi, the guarded pushbuttons shall only be used in special situations, as directed by the checklists. The guard is to protect against inadvertent activation of the pushbutton. The pushbuttons with a yellow ring are there for easy identification in case of smoke in the cockpit. When there's an electrical smoke alert, the procedure is to push those buttons (as directed by the checklist).

There's no technical limitation, but pressing that button for more than a couple of seconds has no other effect than annoying the first officer.

Hotel mode

ATR aircraft don't have APU. It's extra weight. Instead, they have a brake on the propeller gearbox. When the propeller brake is engaged, the gas turbine can run and produce electric power and air conditioning. Bleed air is not used to start the engines. We use GPU or battery power. This video explains more: kzfaq.info/get/bejne/mMuYpKplqd2Ud6M.html

@@FlywithMagnar saw the video and thanks. One more question - After starting # 2 with brake on using battery or GPU you are in Hotel mode. Are you using bleed air generated from # 2 to start # 1 ?

@@jameschen9099 🤦‍♂️no bleed air it's not a 737, electrical starter here you just need electricity

So there another DC starter motor mounted with the accessory gear box also in # 1 ?

No, the logo light is mostly for commercial purpose when the aircraft is on the ground. It also increases the visibility of the aircraft.

@@FlywithMagnar Oh thank you 👍

There are two methods: 1) Distance Measuring Equipment (DME), which is a station on the ground and a receiver in the aircraft. The receiver communicates with the ground station and measures the time a signal takes to move from the aircraft to the ground station and then back to the aircraft. The time gives the distance. It takes the signal 12.36 microseconds to travel 1 nautical mile. The range is line of sight. That is about 120 NM from 10,000 feet. 2) GPS. The range is unlimited.

@@FlywithMagnar Why don't pilots admit the Earth is Flat? Is there a NDA you have to sign to mention anything about flat earth or curvature of earth? I just curious!

No, there's no Non-disclosure Agreement to be signed. Furthermore, we cannot "admit" the Earth is flat, because it's a sphere. This has been known for more than 2,000 years.

@@FlywithMagnar Okay however I disagree with on the shape of the earth!

I'm sorry to hear that.