Date: 201204
Local time of day: 1201-1800
Location: CXO.Airport, TX
Flight conditions: VMC
Light: Daylight
Aircraft: Skyhawk 172/Cutlass 172
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Training
Flight phase: Landing
ATC / advisory: UNICOM CXO
Aircraft component: Aero Charts
Component problem: Improperly Operated
Reporter organization: Personal
Reporter function: Pilot Flying; Instructor
Reporter qualification: Flight Crew Flight Instructor; Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Engineer
Human factors: Confusion; Communication Breakdown
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Landing Without Clearance; Ground Incursion Runway
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert
Contributing factors: Human Factors; Incorrect / Not Installed / Unavailable Part; Chart Or Publication
Primary problem: Human Factors

Narrative: My student and I departed heading north to the Lake Conroe practice area to practice turns; descents; and stalls. I am new to this area of the country in small airplanes. After some instruction it was time for a physiological break and I saw the Lonestar-Conroe Airport close by our position. I was using a handheld GPS for navigation. This GPS has a huge dataBase; but evidently it needed an update. The information I found for CXO did not show a Tower or Ground frequency; even though I could see a Tower on the field. A clearance frequency was listed; however; as well as a UNICOM frequency.South of the field; I called the clearance frequency several times with no response; and then I attempted calling the UNICOM frequency. The ATIS frequency worked and I obtained the airport info; but no response was given on UNICOM. I assumed the Tower had been closed. I surveyed the airport area for traffic; saw none; and called my position in the pattern; while watching the Tower for a sign of activity or a light signal in case the Tower might assume that I was NORDO. I never saw a signal. I landed without event but on rollout saw that the Tower was manned and then saw a green light to taxi clear then another light to cross the next runway to the closest FBO with facilities.Upon shutdown a Ramper advised that the Tower wanted to talk with me. I spoke with the Tower Controller and he wanted to know why I had not contacted him. I explained I did not have the frequency for Tower in my GPS but had attempted contact on the clearance frequency (assuming that it would be guarded) as well as the UNICOM frequency. He knew the clearance frequency which was correct. He was rightly disturbed by my presence in his pattern and I apologized for my blunder. He took my personal info and also gave me the correct frequencies for Ground and Tower. Now; the reason for my stupid moment; and some suggestions that might enhance VFR operators in new areas: The GPS was the only navigation item I had readily available within my reach in the cockpit. The map I did have had slipped behind my student and me. As I mentioned; physiological needs seemed pressing at the time so I made for the closest airport. I did not call on 121.50 for a frequency which would have gotten a response because I did not see my kind of 'emergency' as suitable for the use of the guard frequency.I did not attempt the Approach/Departure frequency since I was well within the boundaries of the airport by that time and more frequency changes were distracting from looking out for traffic; simple as that. What I can suggest since the AWOS /ATIS recording are revised as needed; is that the hours of operation of the Tower be stated; as well as; the primary Tower frequency and the UNICOM in use. Also [I suggest] that the Tower facility monitor their UNICOM frequency.




Synopsis: An instructor pilot and his student landed at CXO (an airport with which the instructor was unfamiliar) without a clearance as the his GPS database did not show a Tower frequency.