Date: 201507
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: Light Transport; Low Wing; 2 Turbojet Eng
Operator: Corporate
Operating under: Part 91
Flight plan: IFR
Flight phase: Descent
Airspace: Class E ZZZ
ATC / advisory: Center ZZZ
Second aircraft: Light Transport; Low Wing; 2 Turboprop Eng
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Confusion; Distraction; Situational Awareness
Second reporter function: Supervisor / CIC; Enroute
Anomaly: ATC Issue All Types; Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Taxi
Result: Flight Crew Executed Go Around / Missed Approach; Flight Crew Took Evasive Action
Contributing factors: Chart Or Publication; Procedure
Primary problem: Chart Or Publication

Narrative: Aircraft X came onto my frequency; enroute to ZZZ. I gave him an initial descent and reviewed the NOTAMs for ZZZ (where he was landing). I observed a number of new NOTAMs that I had not seen before. Among the NOTAMs was this one:'ZZZ 07/025 ZZZ RWY 1/19 ..CLSD.. 1507[day]XD22-1508[day]XD20EST'I asked the pilot if he had the current weather and NOTAMs and for his approach request. He replied that he had weather and NOTAMs and was planning a visual approach. Since the pilot said he had the NOTAMs; I confirmed with him that he was aware of the NOTAM for the runway closure. He replied that he was not familiar with it. I decided to read him that NOTAM and the other NOTAMs since there was a disconnect.The way the NOTAM is written is ambiguous. The 'EST' at the end of the termination time caused me to think 'Eastern Standard Time.' I questioned the time of the time of the NOTAM since there was no 'Z' or 'EST' next to it. I told the pilot we would look into the situation and let him know.I asked the CIC to investigate the NOTAM. He called the airport manager who confirmed that the time was LOCAL time (XD:20). Since it was approximately XA:30; we understood this to mean that the runway was still open and would be open for approximately 3 more hours. I passed this information on to the pilot who intended to land on that runway. The pilot cancelled IFR a number of miles away from the airport and I terminated radar services and issued a frequency change.Another aircraft; Aircraft Y; on the ground at ZZZ called for his clearance and told me he was planning to depart runway 28 since the primary runway was closed. I passed on the information we received from the airport manager to Aircraft Y about the runway being open for a few more hours. Prior to obtaining his release; Aircraft Y called on the frequency again to report that he witnessed Aircraft X change runway at the last minute because runway 1/19 was indeed closed. Aircraft Y told me that the Aircraft X was on approximately a 2 mile final and had to abandon his approach to landing and circle to the other runway to avoid hitting personnel and equipment on the runway.Another aircraft; a VFR Cessna; who was flying over ZZZ reported that he observed 'a dozen vehicles at the approach end of runway 19'. Change the format for NOTAMs to remove any reference to 'EST' as this can easily be confused with 'Eastern Standard Time'. In this case; the issuer meant for 'EST' to mean Estimated. This ambiguity caused a lot of confusion. Apparently even the airport manager was confused about the start time of the NOTAM since he told the CIC the runway was open until XD20 Local time.Better communication needs to be put in place when runways are closed. There should be no doubt or confusion about the status of a runway. The airport manager should have known the runway was closed at that time and should have been very specific in stating that the runway was currently closed.


Second narrative: While working as CIC the controller asked me to help clarify a NOTAM. The NOTAM stated that ZZZ RWY 01/19 would be closed for a week starting today. The NOTAM ended with EST after the published times. I called the Airport Manager to determine whether the closure had started or not; as we were close to the published time. The Airport Manager advised me that the runway was open; not closed; and that it would close at XD20 local. I informed the controller the runway was open. The controller informed the pilot and switched the aircraft to advisory frequency. We then heard from the pilot that someone told him on UNICOM that he could not land on his intended runway of 01/19. The pilot landed on another runway and we were then told that there were a dozen vehicles on the approach end of runway 19. I informed the OMIC [Operational Manager in Charge] of the situation. Runway closures should be more prominently displayed when in effect; not just buried in the NOTAMs.


Synopsis: Controllers report of the letters 'EST' in the end of a NOTAM and the confusion it cost. The Controller thought EST meant Eastern Standard Time; but actually meant estimated. The Controller had aircraft going into the airport to a closed runway thinking it was open. The Controller checked with the Airport Manager who said it was open. An aircraft had to make a missed approach due to men and equipment on the runway.