United 93 was spotted by another aircraft, and, at 10:01, the Command Center advised FAA headquarters that one of the aircraft had seen United 93 waving his wings.
( ( ( ( ( ( ( United 93 ) ( was ( spotted ( by ( another aircraft ) ) ) ) ) , ) and ) ( , ( ( at 10:01 ) , ) ) ) ( ( the ( Command Center ) ) ( ( advised ( FAA headquarters ) ) ( that ( ( one ( of ( the aircraft ) ) ) ( had ( seen ( ( United 93 ) ( waving ( his wings ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (NNP United) (CD 93)) (VP (VBD was) (VP (VBN spotted) (PP (IN by) (NP (DT another) (NN aircraft)))))) (, ,) (CC and) (PRN (, ,) (PP (IN at) (NP (CD 10:01))) (, ,)) (S (NP (DT the) (NNP Command) (NNP Center)) (VP (VBD advised) (NP (NNP FAA) (NNS headquarters)) (SBAR (IN that) (S (NP (NP (CD one)) (PP (IN of) (NP (DT the) (NN aircraft)))) (VP (VBD had) (VP (VBN seen) (NP (NP (NNP United) (CD 93)) (VP (VBG waving) (NP (PRP$ his) (NNS wings)))))))))) (. .)))
United 93 had lost contact with the FAA 30 minutes beforehand.
( ( United 93 ) ( ( had ( ( lost ( contact ( with ( the FAA ) ) ) ) ( ( 30 minutes ) beforehand ) ) ) . ) )
(ROOT (S (NP (NNP United) (CD 93)) (VP (VBD had) (VP (VBN lost) (NP (NP (NN contact)) (PP (IN with) (NP (DT the) (NNP FAA)))) (ADVP (NP (CD 30) (NNS minutes)) (RB beforehand)))) (. .)))