The following is in the Matter of...
Investigation of Accident Involving
Wings West Airlines, Inc., Beech
C99, N6399U, and Aesthetec, Inc.,
Rockwell Commander 112TC, N112SM, near
San Luis Obispo, California, on
August 24, 1984
This following dialog, as derived from pages 4 through 25 of the deposition transcript, was recorded on January 29, 1985, as reported by Milton Reporting, Inc.
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4 11 WILLIAM L. UMBAUGH 12 a witness, was called for examination by the 13 NTSB and, after having been first duly sworn by the 14 Notary, was examined and testified as follows: 15 BY MR. SPEISER: Please be seated, sir. 16 Q Would You please state your full name? 17 A I'm William L. Umbaugh. 18 Q What is your business address, Mr. Umbaugh? 19 A FAA, APM 210, Washington, 800 Independence Avenue. 20 Q In what capacity are you presently employed by the 21 FAA, sir? 22 A I'm manager of the En Route Automation Program
5 1 Branch, and the Program Engineering Maintenance Service. 2 Q How long have you been so employed in that 3 capacity, sir? 4 A Two and a half years; about two and a half years. 5 Q Would you speak up just a little? 6 A I'm sorry. 7 VICE CHAIRMAN GOLDMAN: You folks may want to move 8 over, particularly with this noise in the other room. 9 MR. KOLCZYNSKY: Thank you. 10 BY MR. SPEISER: 11 Q How long have you been employed by the FAA, sir? 12 A Twenty-five years. 13 Q Mr. Umbaugh, would you please give us a brief 14 description of your background and education which has led to 15 your appointment to your present position? 16 A Education began at Pennsylvania State University 17 and follow-on training at Cleveland State University; entered 18 on duty with the FAA in navigational aids area and was 19 trained at the FAA academy. Cumulative time there about two 20 and a half years; entered into the automation business in 21 1964 with the FAA at Air Route Traffic Control Center, 22 Cleveland Center; and I have been here in Washington
6 1 headquarters for nine years. 2 Q Would you please provide us with a brief 3 description of what the responsibilities of your job as 4 branch manager are? 5 A We are responsible for a number of programs, 6 somewhere on the order of ten or twelve. We take care of 7 traffic control requirements and procure air traffic control 8 systems, implement air traffic control systems and then 9 provide the engineering support of the Washington office for 10 those systems. 11 Q In the course of your duties, would this require 12 you to manage or require you to work with the components of 13 two National Airspace Stage A en-route system through the 14 system? 15 A We continue to have engineering support and 16 responsibilities from this office for those systems. 17 Q And is the NAS stage A computer the system that is 18 in use at the Los Angeles Air Route Traffic Control Center, 19 sir? 20 A Yes, it is. 21 MR. SPEISER: Mr. McCarthy? 22 VICE CHAIRMAN GOLDMAN: Mr. McCarthy, proceed with
7 1 the questioning. 2 BY MR. MC CARTHY: 3 Q Within the Los Angeles Center, the Air Route 4 Traffic Control Center, are you aware or could you describe 5 how information from the radar system is processed for 6 display on the individual controller's plan view display, 7 PVD? 8 A Yes, I could. The radar data is digitized at the 9 remote radar site. It is transmitted by way of microwave or 10 telephone line to the center; enters into the central 11 computer complex by way of the peripheral adapter module. 12 The central computer complex, or CCC, performs radar data 13 processing and flight data processing on all the data. 14 It also out puts the flight progress trips and 15 then transmits the radar processed radar data to the computer 16 display channel, or CDC, for display on each of the 17 controller displace or plan view displays, PVD's. 18 Q Good. Thank you. 19 Where, in this flow of information, is the system 20 analysis recording, the SAR, as it is commonly called, made? 21 Where in the process is it tapped off? 22 A Systems Analysis Recordings are made after the
8 1 radar data processing is completed and buffered, ready to be 2 transmitted to the CDC. 3 Q Are you familiar with the National Tracking 4 Analysis Program, the NTAP information? 5 A Yes, I am. 6 Q Could you just give us a brief description of 7 that? 8 A NTAP program is an off-line data reduction and 9 analysis program. That is utilized to reduce, in some 10 summary form, the data that is recorded on the SAR tapes. It 11 was mainly created to assist air traffic in search and rescue 12 type operations. 13 Q Yes. Are you aware that an NTAP data drop of 14 Wings West 628 and the Rockwell Commander 112 involved in the 15 mid-air collision under investigation was prepared? 16 A Yes, I am. 17 Q Have you seen the NTAP data? is A Yes, I have. 19 Q Could You give us a brief description of that 20 data? 21 A The most significant reduction is for a 71 second 22 period. I have the data here. It might help me to look at
9 1 it. 2 Q Certainly. 3 A 71 second period from 1816:22 to 1817:33 Zulu 4 Greenwich mean time, and during that period, the NTAP data 5 shows seven primary code 1200 code target reports for 6 Rockwell 112, four primary 1200 code reports for Wings West 7 628, and then three hits after the Wings West 628 changed the 8 discreet code 621--6721, I'm sorry. 9 Q Right? 10 A This also shows mode C altitude reports for those 11 targets. 12 Q Thank you. Since the NTAP data is derived from 13 the SAR, which is a recording of the data sent to the central 14 display channel or the CDC, is the information taken from the 15 SAR identical to the information transmitted through the CDC 16 to the controller's PVD? 17 A The radar data on the SAR directed to that PVD may 18 or may not be displayed on that PVD, depending on PVD 19 selection keys, filter keys. 20 Q Of course. 21 A If no filter keys are selected, I just think it is 22 necessary to add, there wouldn't be any data.
10 1 Q I agree with that. 2 A Okay. 3 Q Given that the controller had the following 4 selections made, the altitude filter key was from zero to 5 24,200; the non-mode C beacons was selected and all limited 6 data blocks on collated targets was not selected. Given 7 that, would there be any reason why the 1200 target of the 8 Rockwell 112 that was present on the SAR and through the NTAP 9 would not have been displayed on the PVD? 10 A Given the altitude filter limits that you 11 described from up to 24,2, the mode C reporting 1200 codes 12 should have been displayed. 13 Q Okay. Thank you. Do you know of any program or 14 known malfunction or design feature in the CDC that would 15 change or alter the information presented to it as opposed to 16 the output? An internal program is what I'm talking about. 17 A Well the filter keys themselves are an internal 18 program. 19 Q Yes. I'm talking about any malfunction or design 20 feature. For instance, is there a design feature in the 21 software program wherein the computer has too many targets, 22 we have approached capacity? Does it eliminate some of the
11 1 information? 2 A There is such a feature back in the central 3 computer complex, but the data-- 4 Q Central computer complex which is? 5 A C.C.C. 6 Q Only talking about the CDC? 7 A CDC, there is none that I'm aware of. 8 Q Okay. Thank you. Do you know of any feature or 9 malfunction in the CDC that would selectively prevent the 10 display of a single VFR target if other VFR targets were 11 being displayed on the controller's PVD? 12 A When you talk about malfunctions, then as I 13 described or as you mentioned, the filter keys select targets 14 for display based on altitude filtering. 15 Q Yes, but we have already established that we 16 have--we are only interested in the Rockwell 112. We already 17 have established that the Rockwell 112 was at about 3,000 18 feet and was well within our range. 19 A I'm trying to answer the question regarding the 20 possibility of failure that would discreetly or selectively 21 not display a target, and the only way would be if that 22 selective target was in a strata controlled by one altitude
12 1 filter key, the only target in that altitude strata, and that 2 filter key possibly malfunctioned to where it was deselected 3 as opposed to selected. 4 Q Okay. 5 If it were the only target in the strata, would 6 the computer discriminate against a VFR target as opposed to 7 an IFR target or a target that already has a discreet code? 8 A The IFR target with the discreet code could still 9 be displayed by virtue of the other key selections, as I 10 understand the question. 11 Q Is it possible that the 1200 code for the Rockwell 12 commander was masked by another aircraft's data block? 13 A It's hard for me to say that it wasn't possible. 14 I guess it's possible, but I don't have any data to support 15 that there were any other data blocks in the area. 16 Q The software program in the CDC, what is its 17 purpose? The CDC, what is the purpose of the CDC? 18 A Purpose of the CDC? The CDC is basically a plan 19 view display control system, an elaborate plan view display 20 control system that, through about five repetitive update 21 cycles, selects the filter key data from each PVD in a 22 cyclical way; reads that data; takes the data from the CCC;
13 1 using the selective key data, then builds a string of data 2 for update back to that plan view display and then refreshes 3 that display at a rate. 4 Q Good. Then the information, the keys that the 5 controller himself has selected, the display filter keys that 6 he has selected on his scope go to the CDC and then 7 consequently, the information--in other words, what we are 8 talking about is the CDC is controlled by the display filter 9 keys that the controller sets on his PVD? 10 A That's right. 11 Q Great. So is there any reason--you are familiar 12 with how the controller had his scope set up, the information 13 I just gave? 14 MR. JONES: I have to object to that in terms of 15 we are not sure really what the controller had set up. 16 MR. MC CARTHY: That's already-- 17 BY MR. MC CARTHY: 18 Q Given the information that I already have in 19 the record, which we know as a fact as the way the controller 20 had his panel set up, given that, is there any reason that 21 the information on the NTAP data display would not have been 22 display on the R-15 PVD?
14 1 A There is no functional reason why it shouldn't 2 have been displayed. 3 MR. MC CARTHY: That is all I have. 4 VICE CHAIRMAN GOLDMAN: Captain McClure? Are you 5 ready to question? 6 CAPTAIN MC CLURE: Yes, ma'am. I have just one 7 question, sir. 8 BY CAPTAIN MC CLURE: 9 Q It is more for clarification in my own mind. This 10 has to do with this altitude filter key that was set at 11 24,200 feet. Let's take a hypothetical and say that on the 12 PVD, with that filter key set at that position, the altitude 13 filter key, let's assume that there was a VFR 1200 mode C 14 target on the PVD showing an unverified altitude readout out is of 9,500 feet. Would you expect that another mode C 1200 VFR 16 target showing an altitude of approximately 3,000 feet would 17 have been selectively not displayed on the PVD? 18 A No, sir. 19 Q Thank you. 20 MR. MC CARTHY: That's all I have. 21 VICE CHAIRMAN GOLDMAN: Mr. Morio? 22 BY MR. MORIO
15 1 Q Mr. Umbaugh, unfortunately, I wasn't able to hear 2 what your job title was. Could you repeat that again for me? 3 A Manager of the En-route Automation Program, and it 4 is a branch. 5 Q Can you explain the function of your branch? 6 A Function of our branch is to procure air traffic 7 control automation systems to meet air traffic service 8 requirements and implement those systems and provide 9 engineering support after they're in the field. 10 Q Can you explain to me the educational background 11 you received on the NAS radar computer system? 12 A I have been associated, or I started as a central 13 computer complex technician in 1966, so I went through a 14 35-week school on the 80-20 portion, where most of the 15 processing is done. I completed flight data processing, 16 software training and radar data processing training up 17 through 1974, I believe, is when I went to the last FAA 18 academy training on that system. 19 Q You mentioned earlier that you reviewed the Wings 20 West NTAP data from 1817:22 to 1817:33. Did you study any of 21 the information before that? 22 A I spent very little time with that. Reports that
16 1 I've received is that there are no misses in the Rockwell 112 2 data during that time. 3 Q On the Wings West target, if we went back earlier, 4 would you suspect or assume that we would not find any misses 5 on the Wings West targets for some period prior to that, 6 before 1817:22? 7 VICE CHAIRMAN GOLDMAN: 1816:22. 8 MR. MORIO: 1816:22. 9 THE WITNESS: Then you are talking about before we 10 came in. I did not look at that. I have no reason to 11 question that data. 12 BY MR. MORIO: 13 Q If we did want to go back prior to 1816:22, is 14 there any way we could determine how many hits we had on the 15 scope at that point for both aircraft, the Wings West 16 aircraft and the Rockwell? 17 VICE CHAIRMAN GOLDMAN: Are you talking about a 18 hypothetical situation? 19 MR. MORIO: No, this situation. 20 MR. MC CARTHY: I don't understand. 21 MR. MORIO: If we were to go back prior to 22 1816:22, did Bill have any reason to suspect that there would
17 1 be any targets missing sweeps of the radar scope? 2 VICE CHAIRMAN GOLDMAN: Of these two planes? 3 MR. MORIO: Of these two aircraft. 4 THE WITNESS: I certainly have no reason to 5 suspect it. You are talking about the Wings West flight 6 before it came to this, and I don't--I'm not sure I even have 7 that data. 8 BY MR. MORIO: 9 Q The Wings West flight, I believe it was 1816:00, 10 and we only went to 1816:22. What I am saying is that just 11 prior to the :22, did you have any doubt that there would be 12 any hits on the target? I think you are telling me you 13 haven't reviewed that information. 14 A Okay. Let me just be careful here of what the 15 question is. 16 VICE CHAIRMAN GOLDMAN: I don't have all of the 17 documents in front of me, but I would appreciate it if 18 somebody would refresh my memory. 19 MR. MC CARTHY: That is the first target, the 20 16:22. 21 THE WITNESS: Yes, I do think--if you are talking 22 about when he comes off the airport, when he is below 2200,
18 1 that sounds pretty low. 2 MR. MORIO: He called up at 2200 feet at 1816:00. 3 I would think that he would see some hits with the 1200 code 4 at that point. 5 THE WITNESS: I don't believe I have that data. 6 At least I haven't pinpointed that data in the run. 7 BY MR. MORIO: 8 Q But there is no reason for you to suspect that the 9 hits wouldn't be there. 10 VICE CHAIRMAN GOLDMAN: If they were there to be 11 had? 12 THE WITNESS: The only point that comes to mind is 13 that if--you don't always get radar returns when aircraft is 14 on the ground. If you are talking about from it ground to 15 2200-- 16 BY MR. MORIO: 17 Q 2200 feet is where we are talking. 18 A We have the target at 2200, but that is also where 19 this reduction run started. 20 Q And the same question concerning the Rockwell 21 earlier in time. There were, on the NTAP information, I 22 think, tracking all the way from Paso Robles shortly after
19 1 takeoff? 2 A And others who had spent more time with that data, 3 indicated that there were no misses on that track. 4 Q This is my last question. Can you verify that the 5 SAR is taken off the system between the CCC and the CDC? 6 A It's taken out at the--before it is output from 7 the CCC to the CDC. 8 Q Okay. 9 MR. MORRO: Thank you. 10 VICE CHAIRMAN GOLDMAN: Mr. Jones? 11 Mr. JONES: One second, please. 12 (Discussion off the record.) 13 VICE CHAIRMAN GOLDMAN: Okay, Mr. Jones. 14 BY MR. JONES: 15 Q Mr. Umbaugh I believe Captain McClure asked you a 16 question about comparing two aircraft, one at 9500, one at 17 3500. If there were an altitude key malfunction, would there 18 be any reason to see one and not to see another? I'm just 19 wondering, given the stratification that the altitude keys at 20 Palmdale cover, would not one of those altitudes be under one 21 key and another another? 22 A That's right, and to clarify, the altitude filter
20 1 keys that go from the ground, 000 to 24, 2 are really 2 distributed across four keys, so that if we look at that case 3 where you have one at 9500 and one at 3500, they would 4 stradle the first and second of the keys. 5 If, for instance, the lower altitude key, the 6 first key became disengaged, for whatever reason, then the 7 lower altitude aircraft would not be displayed if we are 8 talking about VFR with altitude reporting. 9 Q Also, to follow up a little bit on the question by 10 Mr. McCarthy, is there a situation that you are aware of in 11 which a malfunction could allow a VFR target displaying a 12 beacon code to be displayed while not displaying a VFR target 13 transponder equipped, but displaying--I'm sorry, discreet 14 beacon coding on the first one? 15 Is there a situation that would allow, a 16 malfunction, that would allow a VFR target displaying a 17 discreet beacon code, mode C equipped, to be displayed while 18 not displaying a VFR target mode C equipped but displaying a 19 nondiscreet 1200 beacon code. Is there any kind of 20 malfunction that you are aware of that could accounted for 21 one being displayed and one not being displayed? 22 A Both with mode C; Is that right?
21 1 Q Both mode C, but one discreet beacon and one 2 nondiscreet. 3 A There again, these--if there were failures, and 4 the only one that comes to mind is the one we just discussed 5 where there could be a key malfunction, but it would not be 6 selective, it would only be selective for the strata, and 7 everything in that strata would be affected. Both cases, 8 whether it's a discreet 1200 code, like 1277 or N 1200, the 9 mode C would cause that target to be displayed by virtue of 10 the altitude filter keys. 11 Q If you have--if you don't have the 1200 code 12 entered into your select list, does that affect the 13 situation? 14 A If the 1200 code has mode C reported and is not in 15 the select list, code select list, the difference would be 16 that he would not see the altitude report unless he had his 17 mode C intruder altitude limits set to cover that strata. 18 Q Okay. Maybe I-- 19 A That's a different--do you want me to-- 20 Q Maybe you should elaborate a little bit on that. 21 A As I understand the question, if we have two VFR 22 codes and the VFR code is not in the beacon code select list,
22 1 what is the difference in the display? 2 Q Let me make it more specific for you. Let's take 3 this instance, where we have two aircraft. One is a 1200 4 beacon code, the other is displaying a discreet code. 1200, 5 as we have learned, was not placed--the 1200 code was not 6 specifically placed in the controller's selected list on his 7 display. What I am asking is, is there any malfunction that 8 you are aware of--I'm not asking if it occurred, just if 9 there's any possibility of a malfunction that would allow the 10 discreet coded aircraft to be displayed, but would inhibit 11 the display of the nondiscreet code? 12 A Let me ask for clarification. First of all, in 13 the VFR targets, 1200 code, with mode C reporting? 14 Q Right. We are talking about basically this 15 situation. 16 A Okay. 17 Then there again, the discreet coded target, the 18 6721, given that he had been departed into the system; in 19 other words, air traffic controller had identified him as a 20 discreet target and issued a departure message, then his code 21 would be in the list, beacon code select list, and he would 22 be displayed. Given that the 1200 code was not in the list,
23 1 and similar to the previous example, if the altitude filter 2 key, for instance, became deselected for whatever reason, 3 then the VFR target would not be displayed. 4 MR. JONES: I don't have anything else. I don't 5 have anything else. 6 VICE CHAIRMAN GOLDMAN: I take it this is a 7 somewhat confusing issue, so we are going to go around for a 8 second round. 9 Captain McClure? 10 CAPTAIN MC CLURE: Thank you, I appreciate it. 11 VICE CHAIRMAN GOLDMAN: Perhaps it is not 12 confusing to other people, but it is to me. 13 CAPTAIN MC CLURE: No it is very confusing to me, 14 I assure you. 15 BY CAPTAIN MC CLURE: 16 Q If we could go back to the data that we have in 17 this situation, and at 1816:22 to 1817:33 period, you 18 described seven hits. 19 A Right. 20 Q On the Rockwell Commander, all of them, I believe, 21 VFR 1200 mode C reporting various altitudes. The first four 22 were the Wings West flight.
24 1 VICE CHAIRMAN GOLDMAN: You are making a 2 supposition. Is that what you said, what he just said? 3 THE WITNESS: I said the Rockwell 112 showed seven 4 1200 code hits with appropriate mode C reporting. 5 MR. JONES: During the 71 bit. 6 THE WITNESS: During the 71-second period that we 7 had. 8 By CAPTAIN MC CLURE: 9 Q During the same 71-second period, the first four 10 hits on the Wings West flight 628, were they also 1200 with 11 mode C altitude reporting? 12 A Yes, they were. 13 Q If those four hits were a mode C 1200 information 14 on the Wings West, can you have, and they were portrayed on 15 the PVD to the controllers, can you conceive of any way that 16 the first four hits, for instance, of the Rockwell Commander 17 during the same four periods of time would not been displayed 18 to the controllers on the PVD? 19 A I really can't think of any way. 20 CAPTAIN MC CLURE: I have no further questions. 21 VICE CHAIRMAN GOLDMAN: Mr. Morio? 22 MR. MR. MORIO:
25 1 Q If the accident occurred at approximately 3400 2 feet, how many keys on the controller's board covered this 3 altitude? 4 A One key. 5 Q What altitude range does that key cover? 6 A Oh, from the ground, 000, to 07000. 7 MR. MORIO: Thank you. 8 VICE CHAIRMAN GOLDMAN: All right. There are no 9 further questions from us and no further questions from you. 10 I would declare that this deposition proceeding is speedily 11 concluded, and I thank you very much. We will continue with 12 the investigation...
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