Is It OK to Divert?

There are many reasons to divert, the most common of which is weather. Although you obtained a weather briefing and the forecast was for VFR conditions at the time of your arrival, Mother Nature decided to throw a curveball and now the ceilings are dropping along with the visibility. Or perhaps when you picked up the ATIS or AWOS and noticed the crosswinds or gusts are a bit stronger than you are comfortable with. Or perhaps you have an airsick passenger or that headwind took a bigger bite out of your fuel consumption than anticipated. In all cases the prudent thing to do is divert.

Most pilots learn the art of the divert as part of their cross-country flight training. When planning the flight, select a route that presents options for diversions. Instead of taking that direct route over the mountains, you may want to zigzag a little if there are small airports close by. You do not have to go directly over these other airports, just know that they are out there—perhaps 5 nm from your planned route. If the weather is good enough and your altitude sufficient, you can see them. When using these airports as landmarks on your navlog, write down the pertinent information you will need, such as radio frequencies, orientation and length of runways, etc., so you do not need to fumble with a chart should the divert become necessary.

If your aircraft is equipped with GPS, don't fall into the trap automatically using the NRST (nearest) function. While it is handy, remember that pressing the button to show the nearest airport won’t factor in variables such as weather, airport type, or terrain. The magenta line might direct you into an area of lowering visibility, the side of a mountain unless you climb 3,000 feet (into a cloud deck, no less) or to a grass runway measuring 1,900 feet when you have not learned how to do soft field and short field landings yet.

Once you have figured out where you are diverting to, put a mark on the sectional for your current position, then measure the distance to the divert field. Fair warning: The large plastic plotter can be clumsy in the cockpit, so you might want to use the mechanical E6-B, as it has a measurement scale printed on the side, and you're going to use the wind side of the device to determine groundspeed as well.

Pro tip 1: When you put the wind dot on the E6-B’s wind scale, make it heavy and dark enough that you can see just by glancing at it and leave it on the device. That way you won't have to redo the mark when you are trying to divert. If you are using several different winds for the trip, such as different altitudes, try assigning each one a different symbol (* for winds at 3,000, an X for winds at 6,000, etc.) or use a different color of ink or pencil. Make sure to record the key someplace on your notes—such as the corner of the paper navlog if using that.

Pro tip 2: A typical American disposable pen like a Bic Stic pen with the cap on measures 40 nm on the VFR sectional scale. One of the tools I give my learners is a pen marked off in 10 nm increments, using hash marks cut with a knife and enhanced with liquid paper. Known as "the Magic Pen,” it's a lot easier to use than the plotter for measuring distances.

Pro tip 3: If there is a VOR on the sectional near where you are at the time of the divert, place a straightedge (like the Magic Pen) horizontally on the sectional lined up with where you are and the airport you intend to divert to, then without changing the angle of the straight end, slide it so it sits over the VOR. Read the heading under the appropriate end of the straightedge.

To reach the divert destination, turn the aircraft to the heading. Determine your ground speed and time en route using the E6-B.

When the instructor signs you off for a cross-country flight, the endorsement will list which airports you can land at, as well as the destination and the fields you could potentially divert to, if needed. The instructor who reviews and signs you off for that particular flight should ask about potential landings that could happen en route along with your choice for a divert. These airports will be noted in the endorsement after the phrase "with landings authorized at (insert names here).”

Learners often ask what happens if they land at an airport they were not signed off for. Will they get into trouble? Was the diversion necessitated by a change in weather? The need to refuel? Because it was getting dark and you have not been signed off for night flight? No, you will not or should not be punished for exercising good aeronautical decision making.

Every time you fly you should have an idea of where you go "if" you cannot make it to your original destination. This goes for those out-and-back trips to the practice area. Although we’re taught to anticipate a diversion as part of the cross-country training, many learners would benefit from this training as part of their pre-solo. 

What if you could not land at your home airport because of weather, or even a disabled aircraft on the runway? The savvy instructors prepare for this by making sure the learner has been trained to fly to and from at least one other airport within 25 nm of their home field before they are signed off for their first solo. When the CFI endorses the learner for the first solo, the instructor adds the endorsement for the field 25 nm away. 

I do this with my learners and it has come in handy. When there was a noninjury accident at my airport that closed the runway for several hours, two learners were in the practice area and both diverted to alternate airports. It did wonders for their confidence, and I will admit I was very proud of them as learning had taken place.