U.S. DEPARTMENT OF TRANSPORTATION
FEDERAL AVIATION ADMINISTRATION

Includes: Change 1 effective February 11, 2010
and Change 2 effective October 20, 2011

Appendix 4. NWS RADIOSONDE/HIBAL FLIGHTS

A-4-1. NWS RADIOSONDE/HIBAL FLIGHTS

Use the procedures in this appendix for National Weather Service (NWS) radiosonde balloon releases.

A-4-2. NATIONAL WEATHER SERVICE (NWS) RADIOSONDE BALLOON RELEASES

a. Issue as Aeronautical Information at least 30 minutes prior to the release of a NWS radiosonde balloon under the following conditions:

 1. Delayed release. A radiosonde balloon that will be released later than the scheduled times of 1130 or 2330 UTC.

 2. Special Observations. A release that will be made at times other than those specified for the scheduled observations (1130 or 2330 UTC).

b. The Aeronautical Information shall contain the following information:

 1. The balloon release time.

 2. The time the balloon is expected to reach 10,000 MSL.

NOTE-
A radiosonde ascends at the rate of 800 fpm, reaching 10,000 MSL in 12 minutes and 25,000 MSL in 30 minutes.

c. The locations of radiosonde balloon release points are listed in the Airport/Facility Directories.