ACR X UNAUTH DSCNT BELOW ASSIGNED ALT. ALTDEV.

Narrative

AFTER PASSING OVERHEAD ORD VOR AND BEING VECTORED ON DOWNWIND LEG FOR RWY 27L; I REDUCED SPD TO 190 KTS WHICH WAS MANEUVER SPD. AT ABOUT THE SAME TIME; WE WERE CLRED FROM 7000-5000 FT. THE APCH CTLR THEN CALLED AND ASKED OUR SPD -- WHEN WE REPLIED 190 KTS THE CTLR SCOLDED US ABOUT SLOWING UP WITHOUT NOTIFYING HIM OR ASKING HIS PERMISSION. THIS RESULTED IN 3 ANGRY PLTS AND 1 ANGRY CTLR. I WAS THE CAPT AND I WAS FLYING THE ACFT WITHOUT AUTOPLT OR FLT DIRECTOR. I ASKED THE COPLT TO ASK FOR APCH'S TELEPHONE NUMBER. I WANTED TO DISCUSS WHAT WAS EXPECTED OF US SINCE MANEUVER SPD ON DOWNWIND LEG IS NORMAL AND WE WERE NOT SPD CTLED. THEN APCH ASKED OUR ALT. I WAS AT ABOUT 4600 FT ON MY ALTIMETER AND IMMEDIATELY STARTED TO CLB. THE COPLT REPLIED THAT WE WERE AT 5000 FT AND HE WOULD RECHK THE XPONDER. WE RETURNED TO 5000 FT ON MY ALT IN A FEW SECONDS. AS FAR AS I KNOW THERE WAS NO TFC CONFLICT. I THINK THE FOLLOWING POINTS ARE IMPORTANT: 1) ALL 3 OF US ALLOWED OURSELVES TO BE DISTR BY OUR ANGER AT BEING SCOLDED OVER THE AIR; ESPECIALLY ME SINCE I WAS FLYING THE ACFT. 2) THE EXCURSION VERY PROBABLY WOULD NOT HAVE HAPPENED IF I WAS USING AUTOPLT AND/OR FLT DIRECTOR. 3) THE ALT WARNING SYS ON THE 747 IS PITIFUL WITH A TINY BLUE WARNING LIGHT; AND A WEAK CHIME. 4) I DON'T KNOW IF THE COPLT'S ALTIMETER WAS LAGGING MINE OR IF HE MISSTATED OUR ALT. SUPPLEMENTAL INFO FROM ACN 295548: APCHING O'HARE FROM NW; BEING VECTORED TO LAND RWY 27L. LAST CLRNC FROM APCH CTLR WAS TO 'DSND TO AND MAINTAIN 5000 FT; RESUME NORMAL SPD.' (PREVIOUS CLRNC WAS TO MAINTAIN 250 KTS). APCHING THE O'HARE VOR FROM THE NW; CAPT SLOWED ACFT TO VMA -- ABOUT 180 KTS. SHORTLY AFTER VOR PASSAGE; CTLR INQUIRED AS TO OUR SPD. WHEN TOLD HE BECAME VERY UPSET AND PROCEEDED TO LAMENT AND RANT OVER THE FACT WE'D SLOWED DOWN. WE; THE CREW FOUND THIS PUZZLING AND DISTRACTING; AND ALLOWED THE ACFT TO DSND TO 4600 FT BEFORE IT WAS BROUGHT TO OUR ATTN.