A B737-200 IN CLB AT 14000 FT HAD CABIN PRESSURE WARNING HORN AND CABIN PRESSURE ABOVE 10000 FT WITH CABIN MASKS DEPLOYED. CAUSED BY FAILURE TO SWITCH L AND R PACKS TO ON POS.

Narrative

STARTED ENG #2; CONFIGURED THE BLEED AIR CTL PANEL FOR MAX HEATING AND SINGLE ENG TAXI (R PACK ON; PNEUMATIC ISOLATION VALVE CLOSED; L PACK ON). TAXIED TO RWY 23 FOR DEP AND HELD IN THE HOLDING AREA. APCHING WHEELS-UP TIME; STARTED #1 ENG. AFTER #1 ENG STARTED; I POSITIONED THE PNEUMATIC ISOLATION VALVE TO 'AUTO' AND MOVED A PACK SWITCH (I BELIEVED I HAD MOVED THE L PACK SWITCH TO THE 'ON' POS). STARTED ON THE DELAYED ENG START CHKLIST. INTERRUPTED BY A TKOF CLRNC FROM TWR; I RESPONDED AND CONTINUED WITH THE DELAYED ENG START CHKLIST. WE STARTED TO TAXI INTO POS FOR TKOF; READ AND PERFORMED THE BEFORE TKOF CHKLIST. EACH TIME I REACHED THE LINE ON THE DELAYED ENG START AND THE BEFORE TKOF CHKLIST CONCERNING THE AIR CONDITIONING AND PRESSURE; I LOOKED AT THE BLEED AIR PANEL AND WAS CONVINCED I SAW THE L AND R PACK SWITCHES IN THE 'ON' POS. I; AS THE PF; PERFORMED A NORMAL TKOF AND CLBOUT. WHEN THE CABIN REACHED APPROX 10000 FT; THE CABIN ALT HORN SOUNDED. THE ACFT DID NOT PRESSURIZE. WE WERE SLOW TO RECOGNIZE THIS SIT. THE PNF BEGAN TROUBLESHOOTING AND FOUND THE PACK SWITCHES IN THE 'OFF' POS. REALIZING THE CABIN WAS ABOVE 10000 FT; WE IMMEDIATELY DONNED OUR MASKS. THE PNF PLACED THE PACK SWITCHES TO THE 'ON' POS AND I LEVELED THE ACFT AT APPROX 14000 FT. THE CABIN STARTED TO PRESSURIZE BUT THE CABIN MASKS HAD ALREADY DEPLOYED. AT THIS POINT; WE DECIDED TO RETURN TO THE BUFFALO ARPT. WE MADE AN UNEVENTFUL RETURN; APCH AND LNDG AT BUF.