Altimetry Flashcards
What does QNH mean?
A/C height above Mean Sea Level (MSL)
What does QNE mean?
A/C height above ISA standard pressure level of 1013.25 hPa
What is QFE?
Field elevation
When is QNH set on the altimeter in Australia?
When flying under 10,000 feet
When is QNE set on the altimeter in Australia?
When flying above 10,000 feet
When flying from an area of higher to low pressure, what will occur on the altimeter ?
Altimeter will report an altitude higher than the actual setting.
What must area QNH forecasts be within any low level point within or on the boundary of the appropriate area during the period of validity of the forecast?
5 hPa
What must the Area QNH not differ from between any adjoining area?
5 hPa
What altitude would a 5 hPa difference give?
5 * 30 = 150 feet.
With an accurate QNH set, what should the primary altimeter indication read within airfield elevation?
1) within 100 feet of the published airfield elevation
2) within 110 feet if the elevation exceeds 3300 ft
At what FL are VFR altimeters permitted up to?
FL200
With an accurate QNH set, what is the deviation allowed from the altimeter to the airfield elevation?
1) Should read nominated elevation to within 60 feet.
2) If an altimeter has an error in excess of 75 ft, the altimeter is to be considered unserviceable.
What altitudes should VFR aircraft be flying at if travelling on magnetic track 000 through to 179?
Odd thousands of feet + 500 feet.
What altitudes should VFR aircraft be flying at if travelling on magnetic track 180 through 359?
Even thousands of feet + 500 feet.
What altitudes should IFR aircraft be flying at if travelling on magnetic track 000 through to 179?
Odd thousands of feet
What altitudes should IFR aircraft be flying at if travelling on magnetic track 180 through 359?
Even thousands of feet
What is Transition Altitude (TA)?
- This is the published height AMSL at which pilots climbing to their cruising level change their barometric altimeter datum from QNH to QNE.
- In Australia, this is 1013.25 hPa
What is the Transition Level (TL)?
- The lowest flight level available for use above the TA
- Varies from FL110 to FL125 depending on QNH
What is the Transition Layer ?
- The airspace between the TA and the TL.
- A minimum of 1000 feet
On ascent, when should pilots switch to 1013.25?
When passing above 10,000 feet.
On descent, when should pilots switch to local QNH?
When first entering the transition layer.
What is pressure altitude?
Altitude at which the altimeter sub scale is 1013.25 hPa
What is density altitude?
Pressure altitude taking into account temperature deviation from ISA as well.
Are flights within the transition layer allowed?
No, except for ascent and descent.
