Approaching a Class C boundary with a busy frequency and no clearance
You are VFR in a Piper PA-28, 2,500 feet, 3 nm west of the boundary of Class C airspace. You need to enter to reach your destination. You call: 'Christchurch Approach, ZK-ABC, 3 miles west, 2,500, request clearance to enter controlled airspace.' ATC replies: 'ZK-ABC, standby.' You continue tracking toward the boundary at 110 knots. The frequency is congested with IFR traffic and you hear no further call for 45 seconds. You are now 1.5 nm from the boundary. You have a transponder and are squawking 1200. You know that 'standby' is not a clearance, but you are tempted to enter because you assume ATC is busy and will approve. You have a GPS and can deviate north.
1. What should you do as you approach the boundary and why?
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Remain clear of the Class C airspace. 'Standby' means ATC has received your request and will call you; it is not a clearance. At 1.5 nm and 110 knots you have less than a minute to the boundary, so turn away or orbit outside the boundary. Make a concise call: 'Christchurch Approach, ZK-ABC, 1.5 miles west, 2,500, remaining clear of controlled airspace, request clearance or instructions.' If there is no response, continue to remain clear and divert via the north. Do not squawk 7600 unless you have a confirmed radio failure; a busy frequency is not radio failure. Entering on the assumption that ATC will approve is an infringement and creates a real collision risk with IFR traffic.
2. If you divert north around the airspace, what should you tell ATC and what frequency action should you take?
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Tell ATC: 'ZK-ABC remaining clear, diverting north around controlled airspace, will call again if able.' If you will leave the frequency, say so: 'ZK-ABC leaving frequency, diverting north.' Keep a listening watch if you can. Advising ATC lets the controller release the traffic and stop expecting you at the boundary. Do not simply disappear from the frequency without a call, because ATC may be holding traffic for you. If you later need to enter, make a fresh request with your position and level. The diversion is a normal, safe decision; the unsafe decision would be to enter without a clearance.
3. What are the operational and regulatory risks of entering without clearance?
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Entering Class C without a clearance is an airspace infringement. It can put you in conflict with IFR traffic, force ATC to issue avoiding actions, and trigger a report to the CAA. Your squawk 1200 does not give you identification or separation. ATC may not know your exact position and may have to suspend arrivals or vector traffic around you. The consequences can include enforcement action, loss of licence or medical privileges, and, more importantly, a mid-air collision. The legal and safety consequences far outweigh the convenience of a direct track. If unsure, remain outside and plan a route that avoids controlled airspace.