Narrative:

A lifeguard acfts' alternator had failed in the ZHU airspace. ZHU had lost all contact with this aircraft and believed he was approaching our airspace. My attention was focused on this situation when air carrier X departed iah runway 14L, right turn nebound. On initial contact. Air carrier X reported leaving 3400 for 5000. I stated that air carrier X was radar contact and then attempted to identify lifeguard on 121.5. Air carrier X data block went into coast over the main bang of the north radar. When the data block reacquired on air carrier X mode C indicated 4500. I immediately asked his altitude. He did not respond and I repeated the question. Air carrier X said he was leaving 4700 for 5000. I told air carrier X to maintain 4000, assigned altitude. This altitude was assigned by pre departure clearance. As a result, small aircraft Y at 5000 east of iah northbound and air carrier X nebound 4500 climbing had less than standard separation. Later, via the telephone, the captain of air carrier X stated to the supervisor that the pre departure clearance they received from their ACARS was blurry. Supplemental information from acn 230305. Instead of a normal climb out with a left turn, we were given a right turn to heading 040 degrees within 3 NM. After takeoff, iah tower gave us a frequency change to iah departure control. Upon initial contact with iah departure control we reported passing 3400 ft for what we thought to be the correct altitude of 5000 ft. Iah departure control acknowledged roger, and reported us in radar contact. Shortly thereafter departure called and asked what our altitude was. We responded 4500 for 5000 ft and, thinking that our mode portion of the transponder had failed, asked her what she showed. She replied that we should have leveled at 4000 ft. We immediately returned to 4000 ft. We observed traffic at our 1-2 O'clock position approximately 3 mi away visually and through TCASII, no mention was made by departure control about any traffic in the area and we perceived no conflict with any traffic. It was noted that the ACARS printer clearance readout for altitude was somewhat fuzzy. Neither the captain, first officer, or so remembers who set 5000 ft into the altitude alert window.

Related reports:

Google
 

Original NASA ASRS Text

Title: ACR X NON ADHERENCE TO ATC CLRNC UNAUTHORIZED CLB TO OCCUPIED ALT HAD LTSS FROM SMA Y. PDC MISREAD BY FLC. SYS ERROR. PLTDEV.

Narrative: A LIFEGUARD ACFTS' ALTERNATOR HAD FAILED IN THE ZHU AIRSPACE. ZHU HAD LOST ALL CONTACT WITH THIS ACFT AND BELIEVED HE WAS APCHING OUR AIRSPACE. MY ATTN WAS FOCUSED ON THIS SITUATION WHEN ACR X DEPARTED IAH RWY 14L, R TURN NEBOUND. ON INITIAL CONTACT. ACR X RPTED LEAVING 3400 FOR 5000. I STATED THAT ACR X WAS RADAR CONTACT AND THEN ATTEMPTED TO IDENT LIFEGUARD ON 121.5. ACR X DATA BLOCK WENT INTO COAST OVER THE MAIN BANG OF THE N RADAR. WHEN THE DATA BLOCK REACQUIRED ON ACR X MODE C INDICATED 4500. I IMMEDIATELY ASKED HIS ALT. HE DID NOT RESPOND AND I REPEATED THE QUESTION. ACR X SAID HE WAS LEAVING 4700 FOR 5000. I TOLD ACR X TO MAINTAIN 4000, ASSIGNED ALT. THIS ALT WAS ASSIGNED BY PDC. AS A RESULT, SMA Y AT 5000 E OF IAH NBOUND AND ACR X NEBOUND 4500 CLBING HAD LTSS. LATER, VIA THE TELEPHONE, THE CAPT OF ACR X STATED TO THE SUPVR THAT THE PDC THEY RECEIVED FROM THEIR ACARS WAS BLURRY. SUPPLEMENTAL INFO FROM ACN 230305. INSTEAD OF A NORMAL CLBOUT WITH A L TURN, WE WERE GIVEN A R TURN TO HDG 040 DEGS WITHIN 3 NM. AFTER TKOF, IAH TWR GAVE US A FREQ CHANGE TO IAH DEP CTL. UPON INITIAL CONTACT WITH IAH DEP CTL WE RPTED PASSING 3400 FT FOR WHAT WE THOUGHT TO BE THE CORRECT ALT OF 5000 FT. IAH DEP CTL ACKNOWLEDGED ROGER, AND RPTED US IN RADAR CONTACT. SHORTLY THEREAFTER DEP CALLED AND ASKED WHAT OUR ALT WAS. WE RESPONDED 4500 FOR 5000 FT AND, THINKING THAT OUR MODE PORTION OF THE TRANSPONDER HAD FAILED, ASKED HER WHAT SHE SHOWED. SHE REPLIED THAT WE SHOULD HAVE LEVELED AT 4000 FT. WE IMMEDIATELY RETURNED TO 4000 FT. WE OBSERVED TFC AT OUR 1-2 O'CLOCK POS APPROX 3 MI AWAY VISUALLY AND THROUGH TCASII, NO MENTION WAS MADE BY DEP CTL ABOUT ANY TFC IN THE AREA AND WE PERCEIVED NO CONFLICT WITH ANY TFC. IT WAS NOTED THAT THE ACARS PRINTER CLRNC READOUT FOR ALT WAS SOMEWHAT FUZZY. NEITHER THE CAPT, FO, OR SO REMEMBERS WHO SET 5000 FT INTO THE ALT ALERT WINDOW.

Data retrieved from NASA's ASRS site as of July 2007 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.