| Significance | Code | Meaning |
|---|
| FIR | EGTT | London FIR | | | / | | | Qualifiers | Q | | | | PO | Obstacle clearance altitude | | | CH | changed | | | / | | | Traffic | I | IFR traffic affected | | | / | | | Purpose | N | For immediate attention of aircraft operators | | | B | For inclusion in Preflight Infomation Bulletins | | | O | Operationally significant for IFR flights | | | / | | | Scope | A | Aerodrome information | | | / | | | From flight level | 000 | Surface | | | / | | | Up to flight level | 999 | Unlimited | | | / | | | Centre Latitude | 5204N | 52° 4' North' | | Centre Longitude | 00037W | 0° 37' West | | Radius of area affected | 005 | 5 nautical miles |
| | AMENDED OBSTACLE CLEARANCE ALTITUDE ( OBSTACLE CLEARANCE HEIGHT ) FOR INSTRUMENT APPROACH PROCEDURE NON-DIRECTIONAL BEACON ( L )/ DISTANCE MEASURING EQUIPMENT RUNWAY 21.CATEGORY A,B,C 735 ( 377 ). VMC OBSTACLE CLEARANCE ALTITUDE AND OBSTACLE CLEARANCE HEIGHT NOT APPLICABLE |
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