ATS levels and position reports

The lowest usable level

A usable pressure level must remain clear of the minimum altitude.

Levels and settings

At or below TA use altitude; at or above TL use flight level. Climbing through the layer use flight levels, descending use altitude. The transition level is determined by the appropriate ATS unit according to the published system and current pressure. It is supplied in approach information or clearance as applicable and can be requested.

Altimeter settings passed to aircraft are rounded down to the nearest whole hectopascal under the relevant ATS procedure. When QFE is used, height is referenced to aerodrome elevation except the specified precision/non-precision runway conditions where threshold elevation is used; for an NDB/non-precision approach, a threshold 2 m (7 ft) or more below aerodrome elevation uses the threshold reference as prescribed.

En-route reference

The lowest usable flight level is the lowest pressure level that satisfies the applicable minimum altitude with the current pressure and procedures. Use flight levels at or above it and altitude below it, as applicable. Low QNH can make a nominal level unusable even though its number resembles the minimum altitude.

The same destination’s approach sequence normally places the first holding arrival at the lowest available level, with later aircraft above, subject to operational priorities and clearances. Never self-descend based on sequence or an expected approach time.

Make the next unit’s traffic picture accurate

Report the point, time and reference, not merely that you are airborne.

Normal report

Report over compulsory reporting points, other specified points or intervals and when requested. A normal voice report includes aircraft identification, position, time, level, next position with estimated time and the ensuing significant point. Prefix a standard-pressure level with “flight level”. Include cleared level on the initial call after a frequency change as required, including the current passing level when appropriate.

A shortened report can omit level and next/ensuing points only when the prescribed conditions and ATS directions permit it. With verified Mode C information, level reporting may be omitted when authorised; it is not automatically optional for every initial call. Include airspeed when assigned and required by the reporting procedure.

Automatic and special reports

ADS means automatic dependent surveillance: information is automatically derived from aircraft navigation/other systems and transmitted under the relevant ADS-C or ADS-B arrangements. Dependent means it relies on aircraft-supplied data, unlike primary radar echo ranging.

Special air-reports include severe turbulence or icing, severe mountain wave, thunderstorms in the specified obscured/embedded/widespread/squall-line situations, heavy dust/sandstorm, volcanic ash or significant volcanic activity, and other hazards when needed. Give the position, time, level and observed condition promptly; report a hazard even if a routine position report is not due.

Can you apply the rules?

Four original questions. Choose from the facts, then review the explanation.