Terminal Forecasts Section

METEOROLOGY FLIGHT PLANNING

CHAPTER FOUR

Notice, though, that Part III does not list the whole TAF for the particular aerodrome. It will only

list the one line (or more, including applicable change groups) that applies to the required valid

time, based on the ETA stated on the DD 175 flight plan. As described in Chapter One, the

military requires that destination (and alternate) weather be forecast for the flight to include the

period of +1 hour of the planned ETA.

Another feature of Part III is that the cloud layers are listed immediately after the airfield

identifier, because ceilings are the primary weather factor used to determine whether an alternate

is required. The next column lists the visibility at the field, as this is the other factor in the

requirement for an alternate. Using Figure 4-6, which airfield, SPS or TUL, would be the best

choice for an alternate (assuming all airfields have minimums of 200-1/2)? Review Chapter One

if necessary, because when the weather is problematic, it will be at this point in the preflight

process that the determination of the alternate is made. An aviator can wait until after the

DD 175-1 is briefed to select an alternate, but it must be indicated by the time the DD 175 flight

plan is submitted to Base Operations. The instructor will conduct a discussion of this decision

during class.

To build a weather overview before the weather brief, an aviator would be duplicating the efforts

of the meteorologist to leaf through the many lists of TAFs available. However, an overview of

destination weather can be quickly gathered from the facsimile sources. Aviators can check the

Surface Analysis Chart for observed pressure systems and fronts, and the Surface Prognostic

Chart for a forecast of the same information. Additionally, since TAFs are transmitted less often

than METARs, the reliability of a forecast can be determined during the weather briefing by

comparing existing weather conditions with forecast weather conditions at the destination (or by

comparing the METAR to the TAF).

For your convenience, a summary of the sources that may be used to forecast the weather for

Parts II and III are shown in Figure 4-7.

FLIGHT WEATHER BRIEFING FORM, DD FORM 175-1 4-11