Narrative:

While on climb out after takeoff; at approximately 1500 AGL; the autothrottles moved towards full power during a reduced N1 climb. When the first officer (PF) immediately disconnected the autothrottles; we noticed that VNAV became unavailable as well as no target speed indication on the CDU. I (as the pilot monitoring (pm)) suggested to the first officer that he fly using MCP mode at 280 KIAS/.74 mach up to cruise (fl 360); the autopilot continued to work fine. I continuously monitored the hgs for situational awareness. At cruise (initial level off at fl 340 and then climb to our filed altitude of fl 360 later during the flight); the first officer flew the aircraft with the autopilot in altitude hold and manual control of the autothrottles. We referenced the opc to determine the best cruise altitude/airspeed; as well as verified that the buffet limits on our primary flight displays were accurate. Additionally; I checked the circuit breaker panels for no popped cbs and conducted numerous annunciator recalls and lights tests that revealed nothing during our trouble shooting. Approximately one and one-half hours into the flight; I was able to communicate with maintenance (mx) control via dispatch on ACARS to reveal each of our abnormal indications up until this point; as well as:1. ETA/fuel estimates on the progress page and target speed/turbulence N1/fuel at destination information on the cruise page were missing. 2. The tat reading at fl 340 and fl 360 was -72 degrees C (which I relayed was extremely abnormal); green dashed lines appeared above both N1 gauges and 'FMC speed' nor 'crz' appeared at the top of the primary flight displays and navigation displays; respectively. Mx control then advised me to move the control panel switch from 'normal' to 'both on one / both on two;' the FMC switch from 'normal' to 'both on left / both on right;' as well as conduct the FMC inflight restart checklist (QRH M-13); all with no change in our abnormal indications. While at the half way point to sju; dispatch briefly mentioned the possibility of suggesting that we be sent to a diversion airport but; when I emphasized that the aircraft was flying great with the autopilot engaged and the first officer maneuvering in LNAV and the MCP mode (the way we used to fly these company aircraft before autothrottles and VNAV); I expressed that we were confident and comfortable with continuing to operate this aircraft. Dispatch stated on ACARS to continue to destination. Our descent was normal/uneventful with the first officer having to calculate our profile(s) due to useful data being unavailable on the descent page. We (along with the company flight in front of us) requested the visual to runway 8. The RNAV approach as a backup was partially useful; since LNAV was available and VNAV data was unavailable. I used the hgs in VMC mode for situational awareness as the pm. The weather at the field was 400 sct; 11;000 sct with winds at 200/6 (VMC with a one-two tailwind component). The ride was smooth on the visual approach as the first officer disconnected the autopilot to hand fly from 1000 above tdze to the runway. With this visual approach being flown within parameters; the automatic aural '100 foot' call was made. Immediately following that and prior to the '50 foot' call; the red windshear warning light illuminated along with the 'windshear; windshear; windshear' aural alert. The first officer began his transition to the flare/landing and I allowed him to continue an uneventful; smooth touchdown occurred. After taxiing to the gate; I contacted mx control via dispatch to discuss our options of contract maintenance and/or applying an MEL for our return flight back. Based on me telling mx control that the tat indication on the ground was -32 degrees C (ATIS stated the OAT was 33 degrees C) and all the previous information provided during the flight; it was diagnosed that the tat probe had failed and was inoperative; thereby resulting in the numerous abnormal indications we observed during all phases of the flight. The aircraft was removed from service; I made the appropriate logbook entry before ground personnel remoted the aircraft and company maintenance personnel were to be dispatched to sju with the necessary parts to correct the tat probe malfunction. All of the abnormal indications throughout the flight that were apparently related to the possible tat probe failure were very confusing; most of the symptoms presented had never been witnessed by the first officer or me. While I am satisfied with our handling of the event; dispatch/mx control coordination and the result of getting our passengers to [their next destination] safely and very close to on time; I am not satisfied with how I handled the windshear alert on short final. I (as the captain and pm) should have directed an immediate go-around utilizing the windshear recovery procedure. Whether or not I sub-consciously attributed the windshear warning light/aural to the previous abnormal indications we witnessed during the flight; I should have directed the windshear recovery procedure in accordance with QRH P-3 (my first instinct should always be; under any circumstance; to immediately initiate the correct response as mandated in our company procedures). If the windshear warning light/aural would have then occurred during our second visual approach/landing under the same VMC/calm conditions; I would feel more confident about my subsequent decision to have allowed the second landing to continue under the assumption that the warning light/aural might have been erroneous due to our previous inflight symptoms and possible tat probe failure.

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Original NASA ASRS Text

Title: B737NG Captain reported loss of TAT probe resulted in multiple confusing system errors.

Narrative: While on climb out after takeoff; at approximately 1500 AGL; the autothrottles moved towards full power during a reduced N1 climb. When the First Officer (PF) immediately disconnected the autothrottles; we noticed that VNAV became unavailable as well as no target speed indication on the CDU. I (as the pilot monitoring (PM)) suggested to the First Officer that he fly using MCP mode at 280 KIAS/.74 MACH up to cruise (FL 360); the autopilot continued to work fine. I continuously monitored the HGS for situational awareness. At cruise (initial level off at FL 340 and then climb to our filed altitude of FL 360 later during the flight); the First Officer flew the aircraft with the autopilot in ALT HOLD and manual control of the autothrottles. We referenced the OPC to determine the best cruise altitude/airspeed; as well as verified that the buffet limits on our Primary Flight displays were accurate. Additionally; I checked the circuit breaker panels for NO popped CBs and conducted numerous annunciator recalls and lights tests that revealed nothing during our trouble shooting. Approximately one and one-half hours into the flight; I was able to communicate with Maintenance (MX) Control via Dispatch on ACARS to reveal each of our abnormal indications up until this point; as well as:1. ETA/Fuel estimates on the Progress page and target speed/turbulence N1/fuel at destination information on the Cruise page were missing. 2. The TAT reading at FL 340 and FL 360 was -72 degrees C (which I relayed was extremely abnormal); green dashed lines appeared above both N1 gauges and 'FMC SPD' nor 'CRZ' appeared at the top of the Primary Flight displays and Navigation displays; respectively. MX Control then advised me to move the control panel switch from 'Normal' to 'Both on one / Both on two;' the FMC Switch from 'Normal' to 'Both on L / Both on R;' as well as conduct the FMC Inflight Restart Checklist (QRH M-13); all with no change in our abnormal indications. While at the half way point to SJU; Dispatch briefly mentioned the possibility of suggesting that we be sent to a diversion airport but; when I emphasized that the aircraft was flying great with the autopilot engaged and the First Officer maneuvering in LNAV and the MCP mode (the way we used to fly these Company aircraft before autothrottles and VNAV); I expressed that we were confident and comfortable with continuing to operate this aircraft. Dispatch stated on ACARS to continue to destination. Our descent was normal/uneventful with the First Officer having to calculate our profile(s) due to useful data being unavailable on the Descent page. We (along with the Company flight in front of us) requested the Visual to Runway 8. The RNAV Approach as a backup was partially useful; since LNAV was available and VNAV data was unavailable. I used the HGS in VMC mode for situational awareness as the PM. The weather at the field was 400 SCT; 11;000 SCT with winds at 200/6 (VMC with a one-two tailwind component). The ride was smooth on the visual approach as the First Officer disconnected the autopilot to hand fly from 1000 above TDZE to the runway. With this Visual Approach being flown within parameters; the automatic aural '100 foot' call was made. Immediately following that and prior to the '50 foot' call; the Red Windshear Warning light illuminated along with the 'Windshear; Windshear; Windshear' aural alert. The First Officer began his transition to the flare/landing and I allowed him to continue an uneventful; smooth touchdown occurred. After taxiing to the gate; I contacted MX Control via Dispatch to discuss our options of Contract Maintenance and/or applying an MEL for our return flight back. Based on me telling MX Control that the TAT indication on the ground was -32 degrees C (ATIS stated the OAT was 33 degrees C) and all the previous information provided during the flight; it was diagnosed that the TAT probe had failed and was inoperative; thereby resulting in the numerous abnormal indications we observed during all phases of the flight. The aircraft was removed from service; I made the appropriate logbook entry before Ground Personnel remoted the aircraft and Company Maintenance Personnel were to be dispatched to SJU with the necessary parts to correct the TAT probe malfunction. All of the abnormal indications throughout the flight that were apparently related to the possible TAT probe failure were very confusing; most of the symptoms presented had never been witnessed by the First Officer or me. While I am satisfied with our handling of the event; Dispatch/MX Control coordination and the result of getting our Passengers to [their next destination] safely and very close to on time; I am not satisfied with how I handled the Windshear Alert on short final. I (as the Captain and PM) should have directed an immediate go-around utilizing the Windshear Recovery procedure. Whether or not I sub-consciously attributed the Windshear Warning light/aural to the previous abnormal indications we witnessed during the flight; I should have directed the Windshear Recovery procedure IAW QRH P-3 (my first instinct should ALWAYS be; under any circumstance; to immediately initiate the correct response as mandated in our Company procedures). If the Windshear Warning light/aural would have then occurred during our second visual approach/landing under the same VMC/calm conditions; I would feel more confident about my subsequent decision to have allowed the second landing to continue under the assumption that the Warning light/aural might have been erroneous due to our previous inflight symptoms and possible TAT probe failure.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.