Hi. I have a problem with PMDG 747 Airspeed Indicator. The problem is that during the flight the Airspeed Indicator shows for exaple 356 knots while the Ground Speed shows 512 knots. I was wondering if this a bug or there might be a soloution to this issue. By the way I have FSX on my PC.Thanks

Hi. I have a problem with PMDG 747 Airspeed Indicator. The problem is that during the flight the Airspeed Indicator shows for exaple 356 knots while the Ground Speed shows 512 knots. I was wondering if this a bug or there might be a soloution to this issue. By the way I have FSX on my PC.Thanks

This isn't a problem, they are both showing correctly. Take a look at this link for further information.http://en.wikipedia.org/wiki/AirspeedThe PMDG 744 is a very sophisticated model. I recommend that you take a look at the manual and tutorials to ensure your getting the most out of the experience. :(

Hi,

Hi. I have a problem with PMDG 747 Airspeed Indicator. The problem is that during the flight the Airspeed Indicator shows for exaple 356 knots while the Ground Speed shows 512 knots. I was wondering if this a bug or there might be a soloution to this issue. By the way I have FSX on my PC.Thanks

This is no bug - these speeds are different:groundspeed (GS)true airspeed (TAS)indicated airspeed (IAS)EDIT: F***, not fast enough! :(

Hi. I have a problem with PMDG 747 Airspeed Indicator. The problem is that during the flight the Airspeed Indicator shows for exaple 356 knots while the Ground Speed shows 512 knots. I was wondering if this a bug or there might be a soloution to this issue. By the way I have FSX on my PC.Thanks

No,there is no "solution". It is working correctly. Normally the airspeed indicator is set to KIAS,which means knots indicated airspeed.The reason is, that this speed is within the safe limits of the aircraft at that altitude. The "red bricks" on this aircraft,or in other aircraft,the barber pole needleindicate the safe KIAS.The ground speed is usually significantly higher because the KIAS instrument works by measuring the air coming through the pitot tube,which varies with altitude,temperature and pressure,i.e. the air becomes thinner and colder the higher you go."True airspeed" is a compensated air speed which allows for tailwinds ,crosswinds and headwinds, and the vagaries of the above.Therefore, groundspeed is the actual speed of the aircraft over the ground.All current aircraft work this way.The recent air crash of the airbus off the coast of Brazil is suspected of having a faulty pitot tube as one of the possible causes.Hope this helps somewhat.Ron

Hey Ron, just to add and clarify a little:TAS, ie True Airspeed, does not compensate for tail/headwind. TAS is the airspeed of the airplane as it is truly moving through the wind, regardless of headwinds or tailwinds. TAS and IAS are relatively close to each other while close to the ground and deviate from each other the higher you get due to the decrease in air density and therefore air particles entering the pitot static system as altitude increases. TAS corrected for head/tailwind is where groundspeed comes from. In other words, if there was zero wind, then TAS would equal GS. Let's say an airplane is flying at a TAS of 490 KTAS. A direct headwind of 10 knots will yield a GS of 480, while a direct tailwind of 50 knots would yield a ground speed of 540 knots. Yet in BOTH cases TAS is still 490 knots. So here's the formula for calculating all of the airspeeds:CAS: Calibrated airspeed is the IAS corrected for installation and position errorTAS: Calibrated airspeed corrected for altitude errorsGS: TAS corrected for head and tailwinds.These airspeeds are converted usually in this order using tables and graphs located in the performance section of the Pilots Operating Handbook (POH) that most aircraft have.