Planning your outs along the route and the alternate airports you mark every twenty miles before you leave the ground

Every cross-country flight plan needs more than a route from A to B — it needs a Plan B at every point along the way. By identifying alternate airports every 15 to 20 miles along your course during preflight planning, you ensure that you’re never more than about six minutes from a safe landing option in a typical training airplane. This simple habit transforms a hopeful flight plan into a resilient one.

Why Do You Need Alternates Along Your Entire Route?

Most student pilots build solid navigation logs — checkpoints, headings, fuel burn, winds aloft — but focus entirely on the planned route. That route is Plan A. The gap shows up when something goes wrong mid-flight: engine trouble, weather closing in faster than forecast, a sick passenger, or an electrical failure that kills your radios and GPS.

In that moment, you don’t want to be searching a sectional chart for the first time. Your outs should be planned on the ground, not discovered in the air.

The Airman Certification Standards (ACS) for the private pilot checkride specifically address this. Under the cross-country flight planning task, examiners look for evidence that you’ve identified suitable alternatives along your route. This isn’t a trick question — it’s a fundamental planning skill.

How Do You Identify Alternates Every 15-20 Miles?

Start with your sectional chart or electronic flight planning tool and trace your route. At every 15- to 20-mile interval, identify the nearest airport you could reasonably reach. For each one, note:

• Airport identifier
• Runway length
• Direction from your course line (left or right, and approximate distance in miles)

Why this interval? At 100 knots, 20 miles is roughly 12 minutes of flying. That means at any point along your route, you’re never more than six minutes from a planned alternate — a manageable number even in an emergency.

What Makes a Good Alternate Airport?

Not every airport on the chart qualifies as a practical out. Think critically about each one:

• Prioritize paved runways of at least 3,000 feet. A 2,400-foot grass strip surrounded by trees is on the chart, but it’s not a strong first choice if you’ve never landed on grass.
• Look for airports with fuel and services. If your emergency is manageable — an alternator failure or a rough-running engine still producing power — you may be able to land, get the airplane inspected, and continue or arrange a ride.
• Match alternates to your skill level. A narrow 2,800-foot strip next to a hill is technically an option, but if you’ve only landed at towered airports with wide runways, it’s not one you’ll execute well under stress. Pick alternates where you’d feel confident making a normal landing, because your skills don’t improve in an emergency.

How Do You Add Alternates to Your Navigation Log?

Add one column to the right side of your nav log. Label it “Nearest Alternate.” For each leg or checkpoint, write:

• The airport identifier
• An arrow showing direction from your course (e.g., L 8nm or R 5nm)

This takes about five minutes during planning and dramatically changes your situational awareness in flight.

What Does This Look Like in Practice?

Imagine you’re flying 150 nautical miles from central Pennsylvania to Virginia, cruising at 4,500 feet. Forty-five minutes in, your oil pressure gauge drops — not in the red yet, but trending down. You have maybe 10 to 15 minutes before it becomes a real problem.

With planned outs: You glance at your nav log, see an airport marked 8 miles to your left with a 4,000-foot paved runway, and start your turn. You have a plan. You’re calm. You’re flying the airplane.

Without planned outs: You’re splitting attention between a deteriorating engine and an urgent search of the sectional, or fumbling with the “nearest airport” function on your GPS while oil pressure keeps dropping.

What Factors Change Which Alternates Make Sense?

Four variables should influence your alternate selection:

Weather. If ceilings are lowering from the west, your eastern alternates are more valuable. During preflight, look at the big-picture weather and weight your alternate choices toward better conditions.

Terrain. Over mountainous or hilly terrain, suitable landing sites become fewer and more critical. In these environments, consider routing specifically to stay within gliding distance of landing options. The straight line between two airports is not always the smartest line.

Time of day. A grass strip with no lighting works at 2:00 PM. By 7:30 PM, it’s invisible. If you’ll lose daylight toward the end of your flight, the last third of your alternates must be airports with lighting.

Your comfort level. Be honest. Pick airports where you’d feel confident under stress, not just airports that technically have a runway.

How Should You Handle the Middle of a Long Flight?

Mentally divide your cross-country into segments. You know the airports near your departure well. You’ve studied the destination area in detail. The middle segments are where things get fuzzy — and that’s where alternate planning matters most.

Give the middle of your route extra attention. It’s the portion where you’re farthest from familiar territory and most likely to feel lost if something goes wrong.

Should You Stick Rigidly to Your Planned Alternates?

No. Your ground-planned outs are a starting point, not a contract. Once airborne, update your awareness continuously:

• You might spot a large open field next to a highway that would work for a true engine-out emergency.
• You might notice that a planned alternate has a strong crosswind based on visible smoke or dust.

The plan you made on the ground is your foundation. The decisions you make in the air are what keep you safe.

Key Takeaways

• Plan alternate airports every 15-20 miles along your cross-country route before departure — never more than ~6 minutes from a safe option
• Add a “Nearest Alternate” column to your nav log with the identifier and direction from course; it takes five minutes
• Choose alternates you can actually use — adequate runway length, paved surface, lighting if flying late, and within your skill level
• Give the middle of your route extra attention, where you’re farthest from familiar territory
• Stay flexible in the air — your ground plan is a foundation, not a fixed commitment