An-12 speed

[aviationlover20]

I started to notice that almost all An-12's fly very slow (regardless of head/tailwind). It is a very rare occurrence for them to fly over 300 kts. Do they fly slow to minimize engine tear and wear or is it just the aircraft's econ. cruise speed?

[B2N2]

Headwind or tailwind changes the ground speed and not the speed at which the airplane flies which is True Airspeed.
Quick search on Wikipedia
That performance is actually pretty respectable considering it’s a turboprop and not a jet aircraft.

Performance

Maximum speed (https://en.m.wikipedia.org/wiki/V_speeds#Regulatory_V-speeds): 777 km/h (419 knots, 482 mph)
Cruise speed (https://en.m.wikipedia.org/wiki/V_speeds#Vc): 670 km/h (361 knots, 415 mph)
Range (https://en.m.wikipedia.org/wiki/Range_(aeronautics)): ** With maximum fuel: 5,700 km (3,078 nm, 3,540 mi)

With maximum load: 3,600 km (1,944 nm, 2,236 mi))

[DaveReidUK]

Unfortunately very few An-12s appear to be equipped with Mode S EHS (which sends some useful airspeed parameters).

One that is - AN-12BK UR-CNT of Ukraine Air Alliance - routed over southern UK bound for EMA in late June and, as per the OP's experience, was transmitting figures of 284 KTAS and 191 KIAS at FL240.

[aviationlover20]

Unfortunately very few An-12s appear to be equipped with Mode S EHS (which sends some useful airspeed parameters).

One that is - AN-12BK UR-CNT of Ukraine Air Alliance - routed over southern UK bound for EMA in late June and, as per the OP's experience, was transmitting figures of 284 KTAS and 191 KIAS at FL240.


That's exactly what I was talking about! I also thought that it may be a problem with the transponder because flying 50 kts below the typical cruise speed doesn't make any sense.

[WIDN62]

Turbo-props can save quite a bit of fuel by flying below their normal maximum TAS. I have no knowledge about the An-12, but from memory a C130J can fly at about 350 KTAS. At Long Range Cruise it might fly at 310 KTAS to save maybe 1000+ kgs of fuel over an 8 hour flight. As freight is rarely time critical to an hour or so, maybe that is what they are doing.

[thetimesreader84]

ATP cruise speed was around 200kts indicated at 18,000’, with about a 1200kg/hr burn.

If you dropped it to 180kts indicated, you’d lose maybe a maximum 5 minutes in time, but fuel burn would go down to about 900kg/hr.

all numbers from memory!