Following is a transcript of the radio communications between the New York Air Route Traffic Control Center [R42] in Ronkonkoma, N.Y., and United Airlines Flight 175 (UAL175), which took off from Logan International Airport in Boston on Sept. 11 and then was crashed into the World Trade Center. It includes exchanges with other aircraft in the area at the time. The transcripts were obtained by The New York Times.

8:35:35 -- R42: That's perfect yest go ahead.

8:35:50 -- Unknown: Control for climb AA693.

8:35:55 -- R42: Yea AA693 is your control if you want to climb FDX if you want to turn him too that's fine.

8:36:39 -- USA583: Center USA583 with you at level 350 (35,000 feet).

8:36:54 -- R42: I'm sorry who was that?

8:37:00 -- USA583: USA583 checking in at FL350.

8:37:04 -- R42: USA583 Roger.

8:39:20 -- Unknown: 42-39 see the 823 FL350 reference that guy on left.

8:39:20 -- R42: I gave the FDX turns do what you want reference the FDX.

8:39:40 -- R39: 310.

8:39:45 -- R42: FDX226 contact New York Center on 133.47, good day.

8:39:47 -- FDX3226: 33.4 FDX3226 heavy.

8:39:50 -- UAL457: New York UAL 457.

8:40:11 -- Unknown call: Sector 10 point out west of LRP 712 at FL410.

8:40:18 -- R42: Point out approved.

8:40:32 -- UAL175: UAL175 at FL310.

8:40:37 -- R42: UAL 175 New York center, roger.

8:40:47 -- USA583: New York do a favor were you asked to look for an aircraft, an American flight about about 8 or 9 o'clock 10 miles south bound last altitude 290 — no one is sure where he is.

8:41:07 -- USA583: Yea we talked about him on the last frequency we spotted him when he was at our 3 o'clock position. He did appear to us to be at 29,000 feet. We're not picking him up on TCAS. I'll look again and see if we can spot him at 24.

8:40:20 -- R42: No, it looks like they shut off their transponder that's why the question about it.

8:41:28 -- UAL175: New York UAL175 heavy.

8:41:07 -- R42: UAL 175 go ahead.

8:41:32 -- UAL175: We figured we'd wait to go to your center. We heard a suspicious transmission on our departure from BOS sounds like someone keyed the mike and said everyone stay in your seats.

8:41:51 -- R42: O.K. I'll pass that along.

8:41:56 -- UAL175: It cut out.

8:42:00 -- R42: IGN 93 line.

8:42:01 -- IGN: Go ahead.

8:42:03 -- R42: UAL 175 just came on my frequency and he said he heard a suspicious transmission when they were leaving BOS everybody stay in your seats that's what he heard as the suspicious transmission just to let you know.

8:42:50 -- USA583: Center where do you place him in relation to 583 now?

8:42:55 -- R42: He's off about 9 o'clock and about 20 miles looks like he's heading southbound but there's no transponder no nothing and no one's talking to him.

8:43:20 -- DAL2315: Hello New York good morning DAL2315 passing 239 for 280.

8:43:28 -- R42: DAL2315 New York Center, roger.

8:43:32 -- DAL2433: New York center DAL2433 310.

8:43:39 -- R42: DAL2433 New York Center, roger.

8:43:57 -- USA583: center USA583.

8:44:00 -- R42: USA583 go ahead.

8:44:05 -- USA583: I just picked up an ELT (emergency locator transmitter)on 121.5 it was brief but it went off.

8:44:09 -- R42: O.K. they said it's confirmed believe it or not as a thing were not sure yet so we're still trying going on another aircraft right now and there trying to see what altitude he's at —

8:44:31 -- R42: IGN 93 line East Texas.

8:44:36 -- IGN: go ahead

8:44:38 -- R42: can you turn that DAL2433 a little bit to the right they got that Eagle flight in there and the guy at 310 that they wanted to look at this American to see what altitude he is at can you put him on a 290 heading and stop the DAL1489 beneath him.

8:44:51 -- ZBW IGN: we just put DAL2433 on you we will call him again if we have him we will put him on a 290.

8:44:56 -- R42: I'm not talking to the Delta.

8:44:58 -- ZBW IGN: O.K.

8:45:00 -- R42: DAL2433 New York

8:45:03 -- DAL2433: go ahead.

8:45:05 -- R42: turn right heading of 290 vectors for traffic.

8:45:08 -- DAL2433: DAL2433 at 290 we picked up that ELT, too, but its very faint.

8:45:14 -- R42: O.K. make it a nice tight turn would help traffic 11 o'clock 10 miles northbound turning east-bound at 310.

8:45:21 -- DAL2433: O.K. we'll make it tight

8:45:51 -- R42: DAL2433 thank you for the turn cleared direct SBJ.

8:45:57 -- DAL2433: direct SBJ DAL2433.

8:45:59 -- R42: roger.

8:46:14 -- DAL1489: New York Center DAL1489 heavy out of 290 for 390.

8:46:18 -- R42: DAL683 contact New York Center on 134.32.

8:46:26 -- DAL683: 134.32 thank you.

8:46:28 -- R42: UAL467 contact New York Center on 133.47.

8:46:31 -- UAL467: 133.47 UAL467.

8:46:37 -- DAL1043: good morning New York DAL1043 checking in at FL390.

8:46:38 -- R42: DAL1043 New York Center roger.

8:47:16 -- R42: DAL351 contact New York Center on 134.32.

8:47:21 -- DAL351: 134.32 DAL351.

8:47:26 -- R42: DAL1489 are you on the frequency?

8:47:30 -- DAL1489: DAL1489 out of 310 for 390.

8:47:33 -- R42: DAL1489 New York Center roger cleared direct PTW.

8:47:47 -- DAL1489: direct PTW DAL 1489 heavy.

8:47:40 -- R42: roger.

8:48:50 -- R42: DAL2315 contact the New York Centerr on 134.6, have a nice day.

8:48:59 -- DAL2315: 134.6 DAL2315.

8:49:03 -- R42: 34.6 3-4-point 6.

8:49:38 -- USA429: USA429 leveling off at 350.

8:49:48 -- R42: I'm sorry, who was that?

8:49:50 -- USA429: USA429 leveling at 350.

8:49:51 -- R42: USA429 New York Center roger.

8:50:14 -- Unknown: anybody know what that smoke is in lower Manhattan?

8:50:17 -- R42: I'm sorry say again.

8:50:19 -- Unknown: a lot of smoke in lower manhattan.

8:50:22 -- R42: a lot of smoke in lower Manhattan.

8:50:24 -- Unknown: coming out of the top of the World Trade Center building, a major fire.

8:50:47 -- R42: and which was the one that just saw the major fire.

8:50:52 -- DAL1489: this is DAL1489 we see lower Manhattan looks like the World Trade Center on fire but its hard to tell from here.

8:51:02 -- R42: DAL1489 roger.

8:51:11 -- DAL1489: let us know if you hear any news down there

8:51:15 -- R42: roger.

8:51:32 -- R42: DAL 1043 cleared direct PTW.

8:51:35 -- DAL1043: direct PTW DAL 1043.

8:51:43 -- R42: UAL175 recycle transponder squawk code 1470.

8:51:53 -- R42: UAL175 New York.

8:52:09 -- R42: UAL175 do you read New York.

8:52:14 -- R42: DAL1489 do you read New York.

8:52:16 -- DAL1489: DAL1489 go ahead.

8:52:20 -- R42: O.K. just wanted to make sure you were reading New York — United, United 175 — do you read New York?

8:52:30 -- R42: IGN on the 93 line Kennedy.

8:52:46 -- R42: IGN on the 93 line East Texas.

8:52:52 -- ZBW IGN: IGN.

8:52:53 -- R42: do me a favor see if UAL175 went back to your frequency.

8:52:58 -- ZBW IGN: UAL 175?

8:53:01 -- R42: yes.

8:53:14 -- ZBW IGN: he's not here East Texas.

8:53:23 -- R42: 10 — do you see that UAL175 anywhere and do me a favor you see that target there on 3321 code at 335 climbing don't know who he is but you got that USA 583 if you need to descent him down you can nobody we may have a hijack we have some problems over here right now.

8:53:35 -- R10: oh you do.

8:53:37 -- R42: yes, that may be real traffic nobody knows I can't get a hold of UAL175 at all right now and I don't know where he went to.

8:53:51 -- R42: UAL 175 New York.

8:54:00 -- USA 583: New York 583

8:54:04 -- R42: USA583 go ahead.

8:54:10 -- USA583: yes getting reports over the radio of a commuter hitting the World Trade Center is that nordo [no radio] 76 [Boeing 767] still in the air?