alternate aerodromes; or, if no location identifier(s) have been assigned; (2) Insert ZZZZ and specify the name of the aerodrome in Item 18, following the characters ALTN/. Although alternate airport information filed in an FPL will be accepted by air traffic computer systems, it will not be presented to controllers. If diversion to an alternate airport becomes necessary, pilots are expected to notify ATC and request an amended clearance. NOTE − 1. KDFW0234 KPWA 2. KBOS0304 ZZZZ EXAMPLE − 8. Item 18. Other Information NOTE − 1. Operators are warned that the use of indicators not included in the provisions may result in data being rejected, processed incorrectly, or lost. 2. Hyphens “-” or  oblique strokes “/” should only be used as described. 3. Avoid use of any other special characters in Field 18 information- use only letters and numbers. 4. An indicator without any associated information will result in flight plan rejection. (b) STS/ Reason for special handling by ATS as follows: (1) ALTRV: For a flight operated in accordance with an altitude reservation. (2) ATFMX: For a flight approved for exemption from ATFM measures by the appropriate ATS authority. (3) FFR: Fire-fighting. (4) FLTCK: Flight check for calibration of NAVAIDs. (5) HAZMAT: For a flight carrying haz- ardous material. (6) HEAD: A flight with Head of State status. 5 − 1 − 25 Preflight AIM 1/30/20 (7) HOSP: For a medical flight declared by medical authorities. (8) HUM: For a flight operating on a humanitarian mission. (9) MARSA: For a flight for which a military entity assumes responsibility for separation of military aircraft. (10) MEDEVAC: For a life critical medical emergency evacuation. (11) NONRVSM: For a non-RVSM capa- ble flight intending to operate in RVSM airspace. (12) SAR: For a flight engaged in a search and rescue mission. (13) STATE: For a flight engaged in military, customs, or police services. NOTE − Other reasons for special handling by ATS are denoted under the designator RMK/. (c) PBN/ Indication of RNAV and/or RNP capabilities. Include as many of the descriptors below as apply to the flight, up to a maximum of 8 entries; that is a total of not more than 16 characters. PBN/ RNAV SPECIFICATIONS A1 RNAV 10 (RNP 10) B1 RNAV 5 all permitted sensors B2 RNAV 5 GNSS B3 RNAV 5 DME/DME B4 RNAV 5 VOR/DME B5 RNAV 5 INS or IRS B6 RNAV 5 LORAN C C1 RNAV 2 all permitted sensors C2 RNAV 2 GNSS C3 RNAV 2 DME/DME C4 RNAV 2 DME/DME/IRU D1 RNAV 1 all permitted sensors D2 RNAV 1 GNSS D3 RNAV 1 DME/DME D4 RNAV 1 DME/DME/IRU TBL 5 − 1 − 6 PBN/RNAV Specifications (a) Insert 0 (zero) if no other information; or, any other necessary information in the sequence shown below, in the form of the appropriate indicator followed by an oblique stroke and the information to