APRIL 16: SURIGAO to FORT STOTSENBURG
Flown via Tacloban and Manila. 16c Postage overpaid by 6c.

Backstamped 
CAMP STOTSENBURG, P.I. REC'D. / PAMP. / APR 17 2PM 1931.

The Iloilo to Manila flight (AAMC #43K) took the following route (arrival dates indicated): CEBU, April 12; ZAMBOANGA, April 12; JOLO, April 13; DANSALAN, April 14;  DAVAO, April 15; SURIGAO, April 15; TACLOBAN, April 16, to MANILA on April 17. (Ed Nocom collection)

An earlier discovered unlisted flight associated with the above and illustrated below is the  DAVAO to FORT STOTSENBURG cover plus the ILOILO and TACLOBAN to FORT STOTSENBURG, all in the Chiong collection.

APRIL 15: DAVAO to FORT STOTSENBURG 
Flown via Surigao - Tacloban - Manila

Backstamped CAMP STOTSENBURG, P.I. / REC'D. / PAMP. / APR 17 2PM 1931. 16c Postage overpaid by 8c.
It is highly possible that Camp Stotsenburg addressed covers originating from the other stops from Iloilo to Manila exist.