A B737-800 CREW ON A GAR AT DCA OVERSHOT ALT ASSIGNED BY TWR.

Narrative

ON THE ILS RWY 1; DCA; HVY RAIN SHOWER ACROSS AND W OF THE FINAL APCH COURSE; WE HAD DISCUSSED GOING E OF THE FINAL IN THE EVENT OF A MISSED APCH WITH THE FINAL APCH CTLR; BUT BY THIS TIME WE WERE WITH THE TWR. THE ACFT 3-4 MI IN FRONT OF US HAD JUST RPTED 2 SPD INCREASES; THE FIRST 10 KTS AND THE SECOND 20 KTS; FOLLOWED A COUPLE OF SECONDS LATER BY TWR RPTING A WINDSHEAR ALERT. WE DECIDED TO GO AROUND FROM 1600 FT MSL. THE TWR ACKNOWLEDGED OUR DESIRE; TOLD US TO MAINTAIN 2500 FT MSL AND TURN TO A HDG OF 340 DEGS. ONCE IN THE APCH MODE TRACKING LOC AND GS ON AN ILS; THE B737-800 CAN ONLY BE TAKEN OUT OF THE APCH MODE BY EITHER HITTING THE TKOF/GAR SWITCHES; TUNING AWAY FROM THE ILS FREQ; OR DISCONNECTING THE AUTOPLT; TURNING OFF THE FLT DIRECTORS; AND RE-ENGAGING ANOTHER PITCH AND ROLL MODE. SINCE WE WERE NOT CLOSE TO THE GND; THE PF WANTED TO BE SMOOTH AS WE WENT AROUND (THE GEAR WAS DOWN AND FLAPS 15 DEGS SELECTED); BUT HESITATED AS HE CONSIDERED HIS OPTIONS; THEN ASKED ME IF I THOUGHT HE SHOULD HIT THE TKOF/GAR SWITCHES. RATHER THAN DISCUSS THE OTHER OPTIONS (WE WERE STILL HEADED DOWN INTO THE WINDSHEAR RPTS); I AGREED TKOF/GAR WOULD BE A GOOD PLAN. I PUT 2500 FT IN THE ALT ARMING WINDOW AS HE WENT TO TKOF/GAR; SINCE WE WERE IN SINGLE CHANNEL APCH MODE. THE AUTOPLT IMMEDIATELY DISCONNECTED AND THE ACFT BEGAN TO PITCH UP AS THE PWR INCREASED TO GAR THRUST. I CALLED POSITIVE RATE; HE REPLIED 'TKOF/GAR PWR; FLAPS 15 DEGS....' I SAID THE FLAPS WERE 15 DEGS; POSITIVE RATE; GEAR UP; HE AGREED GEAR UP AND I RAISED THE GEAR. I THEN HIT HDG SELECT TO GET THE ACFT HDG 340 DEGS AND STARTED LOOKING AT MY RADAR PRESENTATION. THE TWR'S ORDER FOR A L TURN AFTER DISCUSSING A R TURN WITH APCH; HAD ME MILDLY CONCERNED THAT WE MIGHT BE TURNING IN A DIRECTION WE REALLY DIDN'T WANT TO GO. I CHKED MY NAV DISPLAY FOR THE WX DEPICTION; I CHANGED RANGE SCALES TO SEE A BIGGER PICTURE; I LOOKED AT THE PF'S PRIMARY FLT DISPLAY AND SAW THE ALT TAPE GOING THROUGH 2200 FT MSL. I SAID; 'HERE'S YOUR 2500 FT;' THE ACFT CONTINUED TO CLB. WE WENT THROUGH 2500 FT MSL AND I LOOKED AT THE ACFT PITCH; WE WERE AT 32 DEGS NOSE UP. I PUSHED FORWARD ON THE YOKE AND SAID WE WERE ASSIGNED 2500 FT; LOOK AT THE NOSE ATTITUDE. THE PF FINALLY REALIZED THE AUTOPLT WAS NOT ENGAGED AND STOPPED THE RATE OF CLB AT 3300 FT MSL. I ASKED THE TWR FOR A HIGHER ALT (THAN 2500 FT). HE FINALLY SAID TO MAINTAIN 3000 FT AND THAT HE HAD ASSIGNED 2500 FT. WE SWITCHED TO APCH AND MADE AN UNEVENTFUL APCH TO LNDG. THE OBVIOUS MISTAKE HERE WAS THE PF FAILING TO CTL THE ACFT MANUALLY WHEN THE AUTOPLT DISCONNECTED (AS IT WAS SUPPOSED TO). THE MORE SUBTLE PROB; THOUGH; IS OUR TENDENCY TO REACT IN OUR MOST FAMILIAR HABIT PATTERN IN AN ABNORMAL SIT. IN THIS CASE THE PF REVERTED BACK TO HIS MD88 HABITS -- PRESS THE TKOF/GA SWITCH AND WATCH THE AIRPLANE GO AROUND AUTOMATICALLY (WHICH HE THEN DIDN'T REALLY DO; BECAUSE HE WAS LOOKING AT THE WX RADAR).