ORA-00904: "S"."AIR_TIME": invalid identifier - oracle

Question

Why does this code show invalid identifier when sum is used in distance and air_time column?
When sum is not used this statement process successfully but using sum I get error? I need to use sum for this statement.
MERGE INTO FACT_COMPANY_GROWTH F
USING (SELECT DISTINCT TIME_ID, FLIGHT_KEY, AEROPLANE_KEY, SUM(DISTANCE) AS TOTAL_DISTANCE, SUM(AIR_TIME) AS TOTAL_AIRTIME
FROM TRANSFORM_FLIGHT T
INNER JOIN TRANSFORM_AEROPLANE A
ON T.FK_AEROPLANE_KEY = A.AEROPLANE_KEY
INNER JOIN DIM_TIME D
ON D.YEAR = T.YEAR
AND D.MONTH = T.MONTH
GROUP BY TIME_ID, FLIGHT_KEY, AEROPLANE_KEY) S
ON (F.FK1_TIME_ID = S.TIME_ID
AND F.FK2_FLIGHT_KEY = S.FLIGHT_KEY
AND F.FK3_AEROPLANE_KEY = S.AEROPLANE_KEY
)
WHEN MATCHED THEN
UPDATE SET
F.TOTAL_AIRTIME = S.AIR_TIME,
F.TOTAL_DISTANCE = S.DISTANCE,
F.TOTAL_NO_OF_FLIGHTS = S.FLIGHT_KEY,
F.TOTAL_NO_OF_AEROPLANE = S.AEROPLANE_KEY
WHEN NOT MATCHED THEN
INSERT(FACT_ID, FK1_TIME_ID, FK2_FLIGHT_KEY, FK3_AEROPLANE_KEY, TOTAL_DISTANCE, TOTAL_AIRTIME, TOTAL_NO_OF_FLIGHTS, TOTAL_NO_OF_AEROPLANE)
VALUES
(NULL, S.TIME_ID, S.FLIGHT_KEY, S.AEROPLANE_KEY, S.DISTANCE, S.AIR_TIME, S.FLIGHT_KEY, S.AEROPLANE_KEY);

Answer 1

USING(
SELECT DISTINCT
TIME_ID,
FLIGHT_KEY,
AEROPLANE_KEY,
SUM(DISTANCE) AS TOTAL_DISTANCE,
SUM(AIR_TIME) AS TOTAL_AIRTIME
...) S
The problem is at UPDATE SET F.TOTAL_AIRTIME = S.AIR_TIME. There are 5 fields defined in S and none is named AIR_TIME.

Answer 2

UPDATE SET
F.TOTAL_AIRTIME = S.TOTAL_AIRTIME,
F.TOTAL_DISTANCE = S.TOTAL_DISTANCE,