| Significance | Code | Meaning |
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| FIR | EGTT | London FIR | | | / | | | Qualifiers | Q | | | | RO | Overflying restriction | | | XX | miscellaneous plain language | | | / | | | Traffic | I | IFR traffic affected | | | V | VFR traffic affected | | | / | | | Purpose | N | For immediate attention of aircraft operators | | | B | For inclusion in Preflight Infomation Bulletins | | | O | Operationally significant for IFR flights | | | / | | | Scope | W | Navigational Warning | | | / | | | From flight level | 000 | Surface | | | / | | | Up to flight level | 016 | 1600 feet QNE | | | / | | | Centre Latitude | 5216N | 52° 16' North' | | Centre Longitude | 00251W | 2° 51' West | | Radius of area affected | 003 | 3 nautical miles |
| | D AND E BAND HIGH INTENSITY RADIO TRANSMISSION AREA ( HIRTA ) IN LOW FLYING AREA 4 AND NIGHT SECTOR 5CN AT POSITION 521617N 0025118W,( AYMESTREY,HERTFORDSHIRE ). RADIUS 2NM.MAXIMUM HEIGHT 530FT ABOVE GROUND LEVEL.25 / 01 / 006 / LFC SAFE DISTANCES CIVILIAN AIRCRAFT 1.1055 NM 170FT ABOVE GROUND LEVEL MILITARY AIRCRAFT SUSCEPTIBILITY VERY LOW 1.0885 NM 62FT ABOVE GROUND LEVEL LOW 1.1070 NM 174FT ABOVE GROUND LEVEL MEDIUM 1.1227 NM 270FT ABOVE GROUND LEVEL HIGH 1.1656 NM 530FT ABOVE GROUND LEVEL |
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