There are many callsigns that pilots can be heard using if you’ve ever listened in to a pilot speaking over the radio.

Wilco is one of these callsigns, but what does it mean, and when is it used?

What Wilco Means in Aviation

In aviation, wilco means that the pilot understands the instructions and “will comply”.

Wilco should only be used when a pilot has understood the instructions and will comply with them, but should not be used when a pilot is given something like heading for traffic, altitude, or clearance to land.

In such instances, ATC (air traffic control) wants the pilot to repeat that information back, and then wilco can also be said.

ATC want a readback for things like taxi instructions or instructions to fly certain procedures to make it explicitly clear that the instructions have been understood by the pilot.

If this is not done, then the air traffic controller has no way to know what the pilot is actually complying with.

What Wilco Means in the Military

In military aviation, wilco has the same meaning as when used by general aviation and commercial pilots.

So, it means, “I understand your message and will comply with it.”

How Wilco Should Be Used

Here are a couple examples of how wilco should be used by pilots:

  • Example 1

ATC: Southwest 145, traffic is a Boeing 747 on 4 miles final for runway 08, report in sight

Pilot: WILCO, Southwest 145

  • Example 2

ATC: Delta 325 turn left heading 120, cleared ILS approach runway 08, report established

Pilot: Heading left 120, cleared ILS approach runway 08, WILCO, Delta 325

As you can see, the more complex the information, the more the need for the pilot to report back what was said to them on their aviation radio to make it explicitly clear that they understood what was said.

Related: What is an ILS in Aviation?

The Origin of the Wilco Call

Wilco very likely has a military origin, as it was and still is a common practice to shorten communications time.

The first known use of wilco is said to be circa 1938.

Wilco is Still Used Today

Yes, the callsign wilco is still in aviation by general aviation, military and airline pilots.

It is perhaps used in some countries more than others, but it can still be heard being used often by pilots in all capacities.

Difference Between Roger and Wilco

Everyone has likely heard the callsign roger before, and probably already know what it means, too.

Roger is simply an acknowledgement of the information received, but does not mean that the pilot will comply.

Wilco, on the other hand, means that the pilot has acknowledged the information received and will also comply with it.

What Roger Wilco Means

Roger wilco means that the information has been received, acknowledged, and a pilot will comply.

However, it is considered redundant, since the “roger” is implied when wilco is used.

Other Unique Terms Pilots Use

Pilots use several other terms that are unique to aviation.

These include:

  • Tree
  • Fife
  • Niner
    Souls on board
  • Pan-Pan
  • Roger
  • Mayday
  • Feet wet
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