FAA Instrument Flight Instructor (FII)IFR Procedures and ApproachesEasy
An instrument student is practicing an ILS approach. During the approach, ATC issues a clearance to 'Maintain 3,000 feet until established on the localizer, cleared ILS Runway 27 approach.' The published glideslope intercept altitude is 2,000 feet MSL. What is the appropriate action for the student and instructor?
- AMaintain 3,000 feet MSL until intercepting the localizer, then descend to 2,000 feet MSL to intercept the glideslope.
- BRequest clarification from ATC, as the clearance is ambiguous regarding glideslope intercept.
- CDescend to 3,000 feet MSL, then to 2,000 feet MSL only after intercepting the glideslope.
- DDescend to 2,000 feet MSL immediately upon receiving the clearance.
Show answer & explanationAnswer & explanation
Correct answer: A. Maintain 3,000 feet MSL until intercepting the localizer, then descend to 2,000 feet MSL to intercept the glideslope.
The clearance explicitly states to 'Maintain 3,000 feet until established on the localizer.' Once established, the pilot is then cleared for the approach and should descend to the published glideslope intercept altitude (2,000 feet MSL) to intercept the glideslope.
Why the other options are wrong
- B. The clearance is not ambiguous; it provides a clear altitude restriction until a specific point, then clears for the approach.
- C. Descending to 2,000 feet only after glideslope intercept is incorrect; the descent to intercept glideslope happens before intercepting it.
- D. This would violate the 'Maintain 3,000 feet until established on the localizer' instruction.
ILS Clearance Interpretation
When ATC issues an ILS approach clearance with an altitude restriction 'until established on the localizer,' the pilot must maintain that altitude until the localizer is intercepted. After being established, the pilot can then descend to the published glideslope intercept altitude.
- Follow ATC altitude restrictions strictly.
- 'Established on the localizer' is the trigger for further descent.
- Descend to glideslope intercept altitude after established on localizer.
Memory trick: Localizer First, Then Glideslope Down.