Luke Air Force Base announced Monday that it will resume flying F-35s Wednesday after 11 days of grounding planes.

The planes were grounded earlier this month because in five instances between May 2 and June 8, pilots reported a lack of oxygen. All five instances came at around the same altitude.

Officials with the 56th Fighter Wing said they did not determine a root cause for the problems with the F-35A Lightning II, but they did eliminate several concerns such as maintenance and aircrew flight equipment procedures.

A release from the Air Force Monday said it would apply five criteria to flights in the short term:

1. Avoid the altitudes in which all five physiological events occurred.
2. Modify ground procedures to mitigate physiological risks to pilots.
3. Expand physiological training to increase understanding between pilot and medical communities.
4. Increase minimum levels for backup oxygen systems for each flight.
5. Offer pilots the option of wearing sensors during flight to collect airborne human performance data.