the NOTAM. Typically SFC means surface height or ground level, and UNL is unlimited height. Other heights are given in feet, flight level, or a combination of the two. Example This is a typical NOTAM for London Heathrow airport: A1234/06 NOTAMR A1212/06 Q)EGTT/QMXLC/IV/NBO/A/000/999/5129N00028W005 A)EGLL B)0609050500 C)0704300500 E)DUE WIP TWY B SOUTH CLSD BTN 'F' AND 'R'. TWY 'R' CLSD BTN 'A' AND 'B' AND DIVERTED VIA NEW GREEN CL AND BLUE EDGE LGT. CTN ADZ This decodes into the following: Series and number: A1234 issued in 2006 (06) Nature of the NOTAM: Replacing (R) NOTAM A1212 issued in 2006 (06) FIR: London FIR (EGTT) Subject: Taxiway (MX) Condition: Closed (LC) Traffic: NOTAM issued for IFR (I) flights and VFR flights (V) Purpose: NOTAM selected for immediate attention of flight crew members (N), for PIB (Pre-flight Information Bulletin) entry (B), concerning flight operations (O) Scope: Aerodrome (A) Limits: FL 000 to FL 999 (000/999) Geographical location: 51°29' N 000° 28' W (5129N00028W) Operation radius of the NOTAM: 5 NM (005) Aerodrome: London Heathrow (EGLL) From: 05:00 UTC 5 September 2006 (060905 0500) Until: 05:00 UTC 30 April 2007 (070430 0500) Category: Aerodromes, air routes, and ground aids Description: Due to work in progress (DUE WIP), taxiway "B South" is closed between "F" and "R" (TWY B SOUTH CLSD BTN 'F' AND 'R'). Taxiway "R" is closed between "A" and "B" (TWY 'R' CLSD BTN 'A' AND 'B') and is diverted via a new green centre line and blue edge lighting (AND DIVERTED VIA NEW GREEN CL AND BLUE EDGE LGT). Caution advised (CTN ADZ). U.S. domestic NOTAMs In the United States, NOTAMs are classified by the FAA into five categories: NOTAM (D) or distant NOTAMs A NOTAM (D) information is disseminated for all navigational facilities that are part of the National Airspace System (NAS), all public use airports, seaplane bases, and heliports listed in the Airport/Facility Directory (A/FD) (e.g., such information as whether or not an airport or a certain facility is usable). NOTAM (D) information includes, among other topics, such data as taxiway closures, personnel and equipment near or crossing runways, and airport lighting aids that do not affect instrument approach criteria, such as VASI. Flight Data Center (FDC) NOTAMs The National Flight Data Center will issue these NOTAMs when it becomes necessary to disseminate information that is regulatory in nature, and they contain such things as amendments to published