T-45C TS INav-08
Fuel, Weather, and Alternate Airfield Planning
Both your destination and alternate weather terminal forecast periods extend from one hour before your
estimated time of arrival (ETA) at each airfield until one hour after ETA. Since your ETA will be different at
your destination and your alternate, you will have different time blocks for examining your forecast
weather. For example, if your ETA at your destination is 0900, your weather forecast period is from 0800
to 1000. If your ETA at your alternate is 0930, you will use a weather forecast period of 0830 to 1030. The
DD form 175-1 provided by the forecaster on the day of flight is the final arbiter of the forecast weather.
Question 1 220.127.116.11
You need to check existing weather for the time of your clearance at your point of departure
and for your _____.
Question 2 18.104.22.168
Your forecast weather is for what period of time?
Filing Criteria Rules for Minimums
The rationale for planning your flight according to stringent weather minimums is to ascertain that the
meteorological conditions at your destination meet the weather minimum criteria. OPNAVINST 3710.7
series dictates the weather criteria to determine whether or not you may file for a destination and whether
or not you must select an alternate. If an alternate is required, these criteria aid you in choosing one that
These weather criteria describe the ceiling in feet AGL and the visibility in sm. For example, minimums
of 3,000-3 mean that your ceiling is 3,000 ft and your visibility is 3 sm.
Refer to the following chart (Figure 1) from OPNAVINST 3710.7 to review the criteria for filing an IFR
Remember to comply with the following IFR filing criteria:
Observe your absolute minimums of 200-1/2 for single-piloted aircraft.
NOTE: The T-45C is considered single-piloted by the FAA beause of its tandem seating,
regardless of how many pilots are in the aircraft.
Use minimums for instrument approach to the probable duty runway based on forecast surface
Use lowest minimums for any published approach to that probable duty runway you are qualified for
and your aircraft is equipped to make.