AP - ПРИВЕД К ГОРИЗ (Level Towards the Horizon)

[Falcon_S]

I don`t know is reported...

 

ПРИВЕД К ГОРИЗ autopilot is broken :joystick:

 

See attachment pls.

[Ironhand]

I don`t know is reported...

 

ПРИВЕД К ГОРИЗ autopilot is broken :joystick:

 

See attachment pls.

It seems to be definitely broken now. When you engage it, the single "Level to Horizon" light illuminates on the AP panel. Once the aircraft is brought within parameters the 2nd Barometric Altimeter Hold panel light illuminates. But it fails to hold the altitude and you continue a descent with level wings.

 

If you then cancel the AP and immediately re-engage Baro Altimeter Hold, the aircraft responds immediately and makes the transition to level flight. So it seems to be the Baro Altimeter Hold function of the ПРИВЕД К ГОРИЗ which isn't working correctly. But Baro Hold used on its own responds correctly.

 

As far as I know, it hasn't been reported.

Edited December 5, 2016 by Ironhand

[DarkFire]

It seems to be definitely broken now. When you engage it, the single "Level to Horizon" light illuminates on the AP panel. Once the aircraft is brought within parameters the 2nd Barometric Altimeter Hold panel light illuminates. But it fails to hold the altitude and you continue a descent with level wings.

 

If you then cancel the AP and immediately re-engage Baro Altimeter Hold, the aircraft responds immediately and makes the transition to level flight. So it seems to be the Baro Altimeter Hold function of the ПРИВЕД К ГОРИЗ which isn't working correctly. But Baro Hold used on its own responds correctly.

 

As far as I know, it hasn't been reported.

 

I was always under the impression that the "level to horizon" button was more or less an emergency feature to recover to level flight in the case of pilot near-incapacitation or disorientation, and isn't meant to be used beyond the actual recovery phase.

[Ironhand]

I was always under the impression that the "level to horizon" button was more or less an emergency feature to recover to level flight in the case of pilot near-incapacitation or disorientation, and isn't meant to be used beyond the actual recovery phase.

It is. It's a "panic button" designed to recover the aircraft in a case where the pilot knows he's disoriented and has lost the horizon. The idea is that it returns the aircraft to straight and level flight.

 

From the two of DCS's manuals:

 

Su-27 (which is admittedly sketchy):

Level up to the horizon. In this mode, the ACS is not switched off by control stick overriding and it has no pitch and bank angle limits. If this mode is on, the push-light switch "ПРИВЕД К ГОРИЗ" (Level up to the horizon) is on in the lower right portion of the front cockpit annumciator panel.

 

Su-25T:

Emergency leveling mode - АУ-ПГ. This mode is selected by pressing [LAlt-3]. It brings the aircraft to straight and level flight from any initial attitude. While the initial bank angle exceeds ±80 degrees, ACS control is applied first in roll, then in pitch. When bank angle is within ±7 degrees and pitch angle within ±5 degrees, the "barometric altitude hold" ACS mode is activated and bank is further reduced to zero.

 

And from Flight Manual:

После приведения самолета к горизонту автоматически включается режим стабилизации Нбар, загорается сигнализатор Нбар и продолжает высвечиваться сигнал ПРИВЕД К ГОРИЗ.

Which I translate loosely as: After automatically bringing the aircraft to the horizon, Barometric Altitude Hold is engaged and the Baro Hold pushbutton illuminates (ACS panel) while the Level to Horizon button (on the annunciator) continues to illuminate.

[DarkFire]

Ah OK, so while the "level to horizon" button is an emergency recovery option, it looks like the ACS is supposed to then activate barometric altitude hold once the aircraft is wings level and to the horizon. So it's the latter feature that isn't quite working correctly.