South Sound residents will notice the visitors. They include three F-16 fighter jets -- the same model flown by the Air Force's Thunderbirds aerial demonstration team.
It's a louder, faster aircraft than the C-17 Globemaster III cargo jets that residents see almost every day flying in and out of McChord.
That's why JBLM on Wednesday announced the arrival of the F-16s from Edwards Air Force Base in California.
"They're here, and the reason they're here is to support the tanker mission," base spokesman Joe Kubistek said.
The Air Force on Friday is expect to conduct its first test flight of a fully equipped model of its new tanker, the KC-46 Pegasus. The tanker flies out of Boeing Field south of Seattle.
A mix of other planes also will be moving through McChord for the tanker tests, JBLM announced Wednesday.
The tests will take place miles above the ground in Northwest airspace that is designated for military and government training. Residents likely will not see training or tanker tests, though they will see and hear different jets taking off and landing from McChord.
Boeing in 2011 won a contract worth $51 billion to develop the tankers. They'll replace the KC-135, a fleet of jets whose age averages greater than 50 years.