2023-01 · NASA ASRS report 1963498
A321 flight crew reported experiencing confusion and difficulty controlling the aircraft when they lost GPS shortly after takeoff.
When we got to the plane; Maintenance was there due to an AFCS (automatic Flight Controls System) issue. They told us they were going to reload some software and expect an hour delay. Instead; they re-racked the module and got the system to test. We learned that the previous flight had multiple GPS Primary Lost Messages during their flight; causing the write up.The following is not a perfect recollection; as many things were happening at the same time and I am not able to 100% correctly remember all events as they were happening too quickly. This is my best effort to recall events as accurately as possible.We took off out of ZZZ Runway XX with flaps 3; APU on; and TOGA power. We were within 8;000 lbs. of maximum TO weight.We reached flap retract speed and started retracting flaps. Around 1300 we got the GPS Primary Lost and it kicked us into heading. Neither of us saw this. During this; my attention was on flap retraction to flaps 1. I initially saw the GPS Primary on the nav display (apparently as it came back from saying GPS primary lost); when the CA (Captain) asked me if we were given a heading. I thought he had heard a radio call for someone else; as we hadn't had a heading assigned (at this point I hadn't seen that we were kicked into heading; I was looking at the GPS Primary message). I said that we were not given a heading. I told the CA that the previous issue was back and apparently hadn't been fixed; referring to the GPS issue. He was still trying to figure out why we were in HDG mode; and asked me again if we were given a heading. We each failed to explain our thoughts to the other; and then I saw that we were in heading mode; and my brain made the connection. Unfortunately; my mouth wasn't in the loop; and I was unable to quickly and clearly explain the situation. I said the previous problem (GPS lost) was what kicked us into heading; but successful communication wasn't happening.Around that time; he asked for flaps up; after takeoff checklist. I glanced to make sure speed was good; then went into my flow. Flaps up; spoilers unarmed; APU bleed off; and APU off; grab checklist. During that; I felt a sinking and acceleration; similar to how a heavy A321 sinks when you go flaps 1 to 0. When I looked down from the checklist; I saw our speed increasing quickly; we were in a bank; and I saw our altitude was lower than I was expecting to see at that point. I knew things did not look right; and assumed the GPS issue was somehow to blame. ATC must have seen us not where we should have been; and they called for us. I responded saying we had an issue with one of our computers; and asked for a heading. They gave us present heading and a 3;000-5;000 ft. block altitude.I still had no idea what was going on to cause the speed and aircraft control issues; as the CA was working on pulling power to slow us and leveling the wings. The CA saw that auto thrust was off; and turned it back on. We set the altitude alert to 5;000 ft. and started a climb. We were given a clearance to initially a heading; then direct to a fix.Once we had things under control; the CA told me that the plane had gone into Alpha floor while I was doing my flow. That was what kicked off the auto throttles and gave us the high speed as the power went up and kicked off the auto thrust.The rest of the flight at cruise was uneventful; but the GPS issue came back multiple times on descent. Since were now familiar with it; these next events were non issues; but still luckily didn't happen in IMC.We should have briefed the possibility of the GPS Primary Lost issue coming back on our flight. It would have been helpful to talk about what it would look like; and how we would handle it. I believe this would have lead us to quickly get the plane back into managed NAV instead of having a communication breakdown while trying to figure out what was going on.It would have been helpful for me to know we went into Alpha Floor when it happened.Instead of sayingthe previous issue was back; I should have called that we had lost GPS navigation. (this is difficult; since I didn't really know that; I just saw GPS Primary; which is what you would expect; but isn't normally on the NAV Display)Instead of asking if we were given a heading; the CA should have stated that we were in HDG; and asked why; or if I had put us into HDG mode.I don't know what lead us into going to Alpha Floor; and I remember looking at our speed before I went flaps 1 to 0; but I now question what I saw; and wonder if I brought them up early.The CA's and my communication broke down; and was not effective when we were kicked to HDG with GPS Primary Lost. We both should have stated the problem we saw instead of being vague and assuming the other pilot was on the same page with our thought process.
Upon arriving to the aircraft; Maintenance was on board fixing a GPS issue which they said they resolved and signed it off. On departure this is what happened with our GPS. On initial climb out; manually flying the airplane; we lost GPS. the aircraft switched from NAV mode to heading mode when I wasn't looking. I asked the first officer why are we in heading mode and he responded because of the previous thing which I did not understand; and I repeated why are we in heading mode; and he repeated because the previous thing I understood I might have missed a radio call or some other system failure; trying to understand what he was saying we were on a NAV departure right as flaps were going from one to up heavy out of ZZZ. while I was communicating with the First Officer (FO); trying to figure out what was going on with the airplane and why the airplane Switched from NAV to heading we lost our GPS and we needed to make an immediate left-hand turn for the nav departure. I told the First Officer to give me a heading from departure and he told Departure Control we had lost navigation at this time; the airplane slowed down to where the auto thrust went into A-Lock. This locked the thrust at full power. I was not sure if the airplane was about to lose other systems so I continued to manually fly the airplane; and I told the First Officer to give me an altitude. Departure Control gave us a block altitude of 3;000 to 5;000 ft. in which the First Officer did not set. Moments later; when I looked back at the altitude; it was at 8;000 ft.; and I told him to set 5;000 ft. and I pulled the thrust out of the TOGA detent into manual. We started to accelerate rapidly; passing 300 kts. I pulled up on the nose; reduced power to help slow the airplane down; and shortly after re-automated the airplane and got the plane back under control. In the future I would have told the FO to give me a heading and turned on the auto pilot to figure out why the airplane lost NAV. Later on; the FO told me he was trying to communicate what he was seeing which was Primary GPS Lost message and that is the reason why the airplane switched from NAV to heading; but he did not articulate what he was seeing and created more confusion.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.
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