EMB ERJ 145 ER/LR
Flight Crew Air Transport Pilot (ATP)
Situational Awareness; Human-Machine Interface
Deviation - Altitude Excursion From Assigned Altitude; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Provided Assistance; Flight Crew Returned To Clearance; Flight Crew Regained Aircraft Control; Flight Crew Overcame Equipment Problem
Aircraft; Human Factors
This event occurred while being vectored for a visual approach to runway XY in ZZZ. The First Officer (FO) was Pilot Flying and I was Pilot Monitoring. ATC had given us a heading to fly and a clearance to descend to 3000 ft. 3000 was entered into the altitude preselect; was confirmed by both pilots and a descent was initiated. At about this time we were also instructed to maintain 180 kts. Sometime later; I noticed that our speed had begun to bleed off considerably; approximately 20 kts and still decaying. I immediately grabbed the thrust levers and increased power attempting to regain our airspeed. At about this time; it was noticed that the preselected altitude had never captured and that the Flight Mode Annunciator had entered into pitch mode at some point. It became apparent that after the aircraft had started its' descent to the preselected ASEL mode had changed to pitch and was never noticed by either pilot. Instead of descending the aircraft had entered a climb at some point and this was not noticed until an appreciable amount of airspeed decay had occurred. At the time that this event was noticed the aircraft was approximately 900 ft. above its' assigned altitude. Shortly after corrective action was begun; ATC queried us about our climbing instead of descending. We replied that we were reversing the climb. The aircraft returned to its' assigned altitude and a visual approach was completed without any further issues.Large decrease in indicated airspeed. The event occurred; because neither pilot noticed the Flight Mode Annunciator (FMA) entering pitch mode. Thrust was added and then the climb was reversed in order to descend back to our assigned altitude.Both pilots need to reaffirm that their primary duty is to fly and monitor the aircraft at all times. Starting with the basics of Heading; Altitude; Airspeed and Performance.
EMB-145 Captain reported while descending the preselected altitude was never captured and the aircraft started climbing.