hi lads can anyone sort out this problem for me when a aircraft coming in to land it never goes down to ground fully is there a setting i go in to thanks
You need to set the QNH for that airfield. Go to the SmartView tab and enter the correct airfield at the top, then make sure the Auto Set QNH box is ticked.
That should help.
Rod
Although bear in mind that, with the QNH set, the height shown just before touchdown will be the airfield elevation, which probably won't be 0ft.
i will try that thanks lads for ter help
i hav tried this lads still no joy any other suggestions when the planes is landing it shows the plane is still up in the air
Quote from: rashers on July 24, 2010, 11:02:59 PMi hav tried this lads still no joy any other suggestions when the planes is landing it shows the plane is still up in the air
What airfield are you talking about ?
shannon ireland
To confirm, you put EINN on the SmartView tab, and ticked the auto-QNH box.
Can you actually receive aircraft all the way down to the ground? And remember, they will stop at 46ft AMSL.
i cant receive them all the way down to the ground that answers tat stops at 46ft another one how do u take sreenshots im not that great at computers just i have a busy day over ireland with us traffic i want to post them tarbat thanks for ur help shannon ireland
It occurs to me that I don't know how RB QNH adjustment actually works (I don't use it), can someone enlighten me ?
Given that aircraft report height/altitude to the nearest 25 or 100ft, relative to 1013.2mb, is the QNH-adjusted height still shown to the same precision ?
http://www.airnavsystems.com/forum/index.php?topic=1048.msg7942#msg7942 probably doesn't fully explain it :(
It is still to the nearest 25ft after the adjustment.
Quote from: tarbat on July 25, 2010, 12:17:05 PM
http://www.airnavsystems.com/forum/index.php?topic=1048.msg7942#msg7942 probably doesn't fully explain it :(
You're not wrong there - I'd forgotten about that thread, but that seems to be all about pilots twiddling things in the cockpit and affecting the altitude transmitted, which I don't think is the case.
Though come to think of it, twiddling the throttle and stick might have an effect :-)
Quote from: DaveReid on July 25, 2010, 01:52:12 PMYou're not wrong there - I'd forgotten about that thread, but that seems to be all about pilots twiddling things in the cockpit and affecting the altitude transmitted, which I don't think is the case.
I'd assumed it was the case, but might well be wrong. Doesn't what the pilot set as the pressure on the aircraft's altimeter affect what altitude gets transmitted?
Quote from: tarbat on July 25, 2010, 04:20:33 PM
Doesn't what the pilot set as the pressure on the aircraft's altimeter affect what altitude gets transmitted?
Not as far as I'm aware - after all, if the transmitted altitude reflected the QNH set by the pilot, then there wouldn't be any need for RadarBox to make any further adjustment.
If you have access to raw data, one of the ELS DAPs (register BDS4,0) includes the actual QNH (in mb) set by the pilot, at least in the case of Airbuses, although many Boeings send a fixed value of 1013.2 even below the transition altitude.
I'm probably out of my depth here, but don't pilots use QFE at low altitudes to set the altimeter, so that their altimeter reads zero when on the deck. Or do pilots always use 1013.2 to set their altimeter, even at low altitudes? And is this the same altitude transmitted on ModeS/ADS/B?
Surely most aircraft can't determine an aititude without the pilot entering an air pressure?
Quote from: tarbat on July 25, 2010, 06:54:18 PM
I'm probably out of my depth here, but don't pilots use QFE at low altitudes to set the altimeter, so that their altimeter reads zero when on the deck.
Yes, that's precisely the purpose of QFE.
QuoteOr do pilots always use 1013.2 to set their altimeter, even at low altitudes?
1013.2 is the setting that Flight Levels are based on, so it's normally only set above the transition altitude (unless of course the QNH on the day happens to be this value).
QuoteAnd is this the same altitude transmitted on ModeS/ADS/B?
The altitude transmitted on Mode S/ADS-B is always based on 1013.2 and not on the altimeter setting, so above the transition altitude it will be equal to the Flight Level. Below the TA it won't be a true altitude AMSL unless the QNH also happens to be 1013.2
Which is where we came in ...
QuoteSurely most aircraft can't determine an aititude without the pilot entering an air pressure?
Quite so - they can determine what Flight Level they are at, but not what altitude.
Quote from: DaveReid on July 25, 2010, 07:37:17 PMThe altitude transmitted on Mode S/ADS-B is always based on 1013.2 and not on the altimeter setting
That's the vital bit of information I've been looking for - thanks. But, does this also apply to military fast jets (eg the Tonkas)?
Quote from: tarbat on July 25, 2010, 07:47:30 PM
That's the vital bit of information I've been looking for - thanks. But, does this also apply to military fast jets (eg the Tonkas)?
I don't know, but I can't see any reason why it would be any different.
Apart from us, I don't thing there is any use being made of Mode S altitude data from low-flying fast jets.
Hi
I would like to make a couple of points. Aircraft do not all do the same thing. A Chipmunk does not have an air data computer ADC so height information will probably come from the front altimeter. That seat is always occupied. Larger aircraft will used the ADC.
QFE is used less often these days. Airfield QNH will be used for landing with the Rad Alt giving touch down information. It is the RAD Alt that calls 30 feet.
1013.2. Use Flight Level
QNH. Use Altitude
QFE. Use Height
Dudley