On August 27, 2008, two controller operational errors (OE) occurred at Reading Regional Airport/Carl A. Spaatz Field (RDG) in Reading, Pennsylvania. The first error occurred at 1614 eastern daylight time (EDT) when the tower controller cleared an aircraft for a low approach to a closed runway without providing an altitude restriction and the second error occurred when another aircraft landed on a closed runway. At the time of the incidents, there were four controllers assigned to the facility. Two certified air traffic controllers were in the tower cab: one controller was working radar approach control/flight data combined at the approach control position, one was working the tower local control/ground control/controller-in-charge positions combined at the local control position, and two controllers were on break. Runway 18/36 was closed and had been closed for 4 weeks. Notices to airmen (NOTAM) 07/003 and 07/014 were in effect. RDG NOTAM 07/003 advised that personnel and equipment were working at the approach end of runway 18; RDG NOTAM 07/014 advised that runway 18/36 was closed from 0700 to 1700 EDT Monday through Friday. The runway closure was broadcast on the automatic terminal information service (ATIS) and posted on the status information area (SIA) board in the tower cab. Both incidents occurred during day visual meteorological conditions with 10 miles visibility. Runway 18/36 was dry. At approximately 1609, the RDG arrival controller, working beside the local controller in the tower cab, cleared the pilot of N44763, a PA-28, for a GPS RWY 18 approach and directed the pilot to contact the tower. After contacting the tower, the RDG local controller cleared the pilot of N44763 for a low approach to runway 18, a closed runway, without an altitude restriction. The second error occurred about 10 minutes later when a Cessna 172 landed on runway 18 which was closed. At 1621, the arrival controller instructed N54020, a Cessna 172, to enter a left downwind for runway 13 and to contact the tower controller. On initial contact, the pilot of N54020 stated that he was established on a left downwind for runway 13 and was advised "... left traffic runway 13, pattern altitude 1400, begin descent, report mid-field downwind." At 1623, N56FE, a Cessna Citation, checked in with the arrival controller and was provided radar vectors for a visual approach to runway 13. The local controller was aware that the arrival controller was required to vector the Citation behind the Cessna 172, which was slower. In an effort to expedite services being provided N56FE, the local controller queried the pilot of N54020 if he could accept runway 18 with the wind 130 degrees at 6 knots. The pilot of N54020 responded, "Ah sure, if that is what you would like us to do." At 1625 the local controller said, "Cessna 020 thank you, you're crossing over the [runway 18] approach end now you can make a right turn around into final, runway 18 cleared to land, hold short runway 13, landing traffic, 3000 feet available". At 1627 p.m., N54020 landed without incident. FAA Order 7110.65, Air Traffic Control, Pilot Controller Glossary, defines "closed runway" as "a runway that is unusable for aircraft operations". Paragraph 3-1-1, "Provide Service" states: "Provide airport traffic control service based only upon observed or known traffic and airport conditions". Paragraph 3-10-10, "Altitude Restricted Low Approach" states: "A low approach with an altitude restriction of not less than 500 feet above the airport may be authorized except over an aircraft in takeoff position or a departure aircraft. Do not clear aircraft for restricted altitude low approaches over personnel unless airport authorities have advised these personnel that the approaches will be conducted. Advise the approaching aircraft of the location of applicable ground traffic, personnel, or equipment". Runway 18 had been closed from 0700 to 1700 EDT Monday through Friday for nearly four weeks preceding these errors. The runway closure facilitated construction of a safety area at the approach end of runway 18. On August 27, 2008, there were no personnel or equipment on or near the runway. On the morning of August 27, 2008, Airport Operations issued a memorandum for the record stating in part: "lighted X's shall be required for ALL runway closures. The X's are to be located at each end of the runway end over the numbers". This memo had been faxed to the RDG tower facility management on August 27, 2008, at 0810; however, the X's were not on the runway at the time of the incidents.