ALT EXCURSION E OF PMM; MI.

Narrative

AWARENESS OF ALT 'ENGAGE' FOR ALT 'HOLD' ON B727. LEVELED OFF AT FL220; (22000 FT). WAS DURING INITIAL DSCNT PORTION OF FLT; GOING INTO ORD. AFTER LEVELING OFF AT FL220; I ENGAGED AUTOPLT; WITH ALT HOLD. NORMALLY I CHK TO VERIFY ALT HOLD IS; IN FACT HOLDING. SUBSEQUENT TO ENGAGING; I LOOKED DOWN IMMEDIATELY TO CHK APCH CHARTS; ARPT DIAGRAMS; ETC. APPROX 15-30 SECONDS AFTER LEVELOFF; I LOOKED UP AGAIN AND SAW ALT OF 21750 FT; AND DSNDING. I IMMEDIATELY CLICKED OFF THE AUTOPLT; ADDED PWR; AND CLBED IMMEDIATELY TO ASSIGNED ALT; FL220. NO CONFLICTS; NO ATC QUERY. JUST; TO STATE; IF YOU 'SET A SWITCH;' VERIFY APPROPRIATE ENGAGEMENT OR ACTION IN PLACE. I LOOKED DOWN TOO QUICKLY. TO VERIFY IS THE UTMOST; ESPECIALLY ALT HOLD. DSCNT WAS SUBTLE; AND NO ONE NOTICED IT IN THE COCKPIT. SUPPLEMENTAL INFO FROM ACN 488160: WE HAVE NO SOPS REGARDING AUTOPLT ENGAGEMENT PROCS UNLIKE THE GLASS COCKPITS; SO THE PNF MIGHT NOT BE IN THE AUTOPLT ENGAGEMENT MODE LOOP. WITH ONLY A SWITCH POS BEING THE INDICATION FOR ALT HOLD; WHICH IS ON THE CTR CONSOLE; IT IS A VERY EASY ONE TO MISS. I AM SURPRISED THERE ARE NOT ANY 'AUTOPLT ENGAGED' AND 'ALT HOLD' ANNUNCIATOR LIGHTS ON THE INST PANEL. NEW SOPS AND OR THESE LIGHTS WOULD PROBABLY HELP ELIMINATE THIS TYPE OF PROB.