Poor Fred : From recent news:
The Ministry of Emergency Affairs of the Tomsk region said that the aircraft had a fault sensor of the left chassis. When taking off to land at an altitude of 600 meters, the crew that the alarm was running, indicating problems with the hydro system, then requested a visual confirmation of the release of the chassis stand.

And is it impossible to equip aircraft with video cameras directed at the chassis, doors, wings, etc., to independently see the release / failure to release the chassis, the opening / failure to open the doors, etc.? to

WolferR: And why? Instead of staring at the screen, trying to find out what is happening through the dim, jumping picture, it is easier to look at the sensor indicator - the desired light bulb is lit or not.

FP-92: You probably did not deal with more or less sophisticated automatic equipment. The fact that the light bulb burned or did not burn is not always consistent with the physical performance or failure to perform the command. Especially if it did not burn.

Sukin: There are also, as far as I know, possible problems such as "outcome incomplete" and "outcome but not stuck". The most reliable thing to do over the chassis of a luke and one pilot to climb and check if everything is okay there or not. You can shake your hands and knock if necessary. The other will hold him at his feet.