A question regarding 'level flight thrust'

[ex902]

Hello,

I read a comment as follows:

"A level flight at idle thrust is also possible, when aircraft aim for a fast deceleration at constant altitude"

I am not a pilot so I do not want to say something wrong, however, how can an aircraft maintain a constant altitude, during deceleration, at idle thrust?

Is this a completely wrong statement or could it be reasonable in a certain view?

Thank you for your time.

[AerocatS2A]

It is decelerating. It can't maintain constant altitude for ever, it eventually won't have enough speed to be able to create enough lift. Until that happens though, it can happily maintain altitude. You need to progressively pitch up because as the speed reduces the angle of attack of the wings must be increased to maintain the same lift.

[PDR1]

Or just stall, plummet and explode inside one of the hospitals, nuclear reactors or schoolsful of disabled children which seem to gather underneath all aeroplanes when flying (according to the safety case I'm reviewing at the moment)

[RAT 5]

ex902: as you're not a pilot, consider this. You are in a car, level road at 120kph, approaching a steep descending hill. If you reach the hill at 120kph you will have to brake to stop accelerating even with your foot off the accelerator i.e. at idle. One technique is to take your foot off the power and let drag/friction slow you down so you reach the hill at 50kph and then coast down the hill and slowly accelerate again. If you take your foot off too early the car will stop before you reach the hill and you'll need some power to reach the hill top. Stopping in a car is an option.
A jet aircraft wing needs speed to fly and create lift. It can be cruising at 450kph and also still fly level at 200kph. The wing has a max & min speed to create lift for level flight. The lower the speed the higher the nose of the aircraft points upwards. Aircraft are made slippery, so if you descend at 450kph and want to slow down to 200kph it will be difficult and take a long time/distance. It's easier to use idle thrust & drag to slow down to 200kph in level flight then find an angle to descend on that maintains 200kph at idle thrust. If you descend too steeply you will accelerate; too shallow and speed will reduce . There will be an angle just right for 200kph; you need to find it. That is controlled with elevator and the jet will be descending at idle thrust, almost as a glider.
As you reduce speed the nose rises to keep sufficient lift, but if you continue to slow down the speed will become insufficient to create lift and the wing will stall and the a/c will descend in a semi-uncontrolled manner due to gravity. The recovery is to lower the nose to accelerate the wing to 'flying speed' or use thrust to achieve the same, or a combination.
Stopping an a/c is NOT an option. Flying is all about energy management in vertical dimension.