Narrative:

Immediately following takeoff we experienced a course deviation incident. It was the first officer's leg; and all aspects of the preflight and taxi out went normally and no indications were made that anything was amiss. We lined up on 8R to depart atl on the POUNC2 departure. All flight and navigation instruments were showing normal. We had an abnormal takeoff procedure due to an MEL on the aircraft. The procedure called for us to leave the landing gear down for 10 min before slowing and retracting. We followed this procedure as instructed by the MEL; and other than the added narrative and attention; had no issue complying. The course deviation happened after the first officer called for speed mode; nav mode; and then autopilot. After arming navigation mode; I verified that the fcp lights around the button illuminated on the captain's side pfd FMS showed armed and then active. The auto pilot was armed and we continued with our flight profile. When checking on with departure I noticed that our flight path didn't appear to be correct and despite my side pfd showing FMS active; it wasn't following the correct course. Looking at the first officer's side; his course needle had disappeared and the aircraft appeared to have remained on runway heading. We quickly acted together to try and correct the incident. While I spun the heading bug to our first fix of hrshl and switched from navigation mode (which was still illuminated) to heading mode; the first officer cycled his navigation source on his side. I quickly activated the fcp to fly from my side and reactivated navigation mode. Autopilot quickly captured and flew the correct course from the captain's side. This all occurred from about 1;200 feet to approximately 3;000 feet. In the meantime we were pulling up flaps and accelerating as is required on the departure procedure. I am not aware of exactly how far off course we deviated before catching the error; but the initial heading of 072 was not flown when it should have been. Air traffic control also identified the course deviation; and queried us at about the same time we were taking corrective action. I initiated a fcp event on the aircraft in hopes the company could look into the event to piece together a more complete picture of what may have occurred. Following the event we leveled off in cruise flight and switched the fcp back to the fos side to see if it had any other issues; which it did not. We elected to continue flying on the ca side; after checking the fos just in case and called maintenance once we landed [at destination]. Maintenance control seemed to believe the issue was a temporary loss of GPS signal. If it was indeed a loss of GPS signal as maintenance control indicated; I don't know if there are some sort of steps that could be made to prevent that in such a critical phase of flight? In the future I will be more certain to verify the autopilot does indeed make the correct turns as expected shortly after arming new flight modes; or arming the autopilot. If we had identified the problem as soon as the plane was supposed to have made the turn and failed to do so; we could have flown the departure procedure manually without incident.

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Original NASA ASRS Text

Title: CRJ-200 Captain reported a track deviation resulted when they temporarily lost the GPS signal for unknown reasons.

Narrative: Immediately following takeoff we experienced a course deviation incident. It was the First Officer's leg; and all aspects of the preflight and taxi out went normally and no indications were made that anything was amiss. We lined up on 8R to depart ATL on the POUNC2 departure. All flight and navigation instruments were showing normal. We had an abnormal takeoff procedure due to an MEL on the aircraft. The procedure called for us to leave the landing gear down for 10 min before slowing and retracting. We followed this procedure as instructed by the MEL; and other than the added narrative and attention; had no issue complying. The course deviation happened after the First Officer called for speed mode; Nav Mode; and then autopilot. After arming NAV mode; I verified that the FCP lights around the button illuminated on the Captain's side PFD FMS showed armed and then active. The auto pilot was armed and we continued with our flight profile. When checking on with departure I noticed that our flight path didn't appear to be correct and despite my side PFD showing FMS active; it wasn't following the correct course. Looking at the FO's side; his course needle had disappeared and the aircraft appeared to have remained on runway heading. We quickly acted together to try and correct the incident. While I spun the heading bug to our first fix of HRSHL and switched from NAV mode (which was still illuminated) to HDG mode; the First Officer cycled his NAV source on his side. I quickly activated the FCP to fly from my side and reactivated NAV mode. Autopilot quickly captured and flew the correct course from the Captain's side. This all occurred from about 1;200 feet to approximately 3;000 feet. In the meantime we were pulling up flaps and accelerating as is required on the Departure procedure. I am not aware of exactly how far off course we deviated before catching the error; but the initial heading of 072 was not flown when it should have been. Air Traffic Control also identified the course deviation; and queried us at about the same time we were taking corrective action. I initiated a FCP event on the aircraft in hopes the company could look into the event to piece together a more complete picture of what may have occurred. Following the event we leveled off in cruise flight and switched the FCP back to the FOs side to see if it had any other issues; which it did not. We elected to continue flying on the CA side; after checking the FOs just in case and called Maintenance once we landed [at destination]. Maintenance Control seemed to believe the issue was a temporary loss of GPS signal. If it was indeed a loss of GPS signal as Maintenance Control indicated; I don't know if there are some sort of steps that could be made to prevent that in such a critical phase of flight? In the future I will be more certain to verify the autopilot does indeed make the correct turns as expected shortly after arming new flight modes; or arming the autopilot. If we had identified the problem as soon as the plane was supposed to have made the turn and failed to do so; we could have flown the departure procedure manually without incident.

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.