Date: 201907
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
Reporter organization: Air Carrier
Reporter function: Flight Attendant In Charge
Human factors: Communication Breakdown; Time Pressure
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
Detector: Person Flight Attendant
When detected: Pre-flight
Result: General None Reported / Taken
Contributing factors: Company Policy; Environment - Non Weather Related; Human Factors; Procedure; Weather
Primary problem: Company Policy

Narrative: When I arrived at the gate; the agent informed me that the pilots were late inbound and wouldn't be landing until [time] and I asked if we were still planning on boarding on time the agent said yes. When I got onto the airplane and briefed with my crew we discussed that the plane is a little warm and we hadn't been catered yet and and it's better to let the passengers be in the terminal for 10 more minutes so when the agent came down to ask if we were ready I asked her if we could board at 30 or even 35 prior to departure so the passengers weren't stuck on a hot plane for longer than they had too. She agreed. The agent then came down and informed me that they had called the inflight supervisor and she told them they needed to board on time. During boarding the supervisor showed up to the plane and I told her my reasoning for wanting to wait that having the passengers sit and wait on the plane was not as comfortable or safe as letting them be in the terminal where they can freely use the restroom and be comfortable; she informed me that on time departures and the agents rubric of time was very important and that we needed to stick to that and that at [time] the pilots had already landed. She also informed me that the agents told her we wanted to wait for the pilots to arrive to board which was not the case and when the agent came down she apologized for not being able to wait and told me she did not tell them we wanted to wait until pilots arrived. The agent was done boarding the plane at 20 min prior to departure. The plane was so hot we sent the last passenger a commuting pilot up to the agents to inform them that it was too hot on the plane. The commuting pilot looked out the window and said there is no ground air hooked up to the plane. The agent came down and said the pilots should be here soon.The pilots arrived at the airplane at [time] and the captain told me it was 90 degrees on the plane and he would get the air going ASAP. The captain also informed me that they did not land until [time] and rushed over here as soon as they possibly could. I should have refused to let the agent board due to the unsafe temperature on the plane and no way to communicate with the agent at the top of the jetway without pilots on the plane.If you're going to board a flight with no pilots and they plan on having passenger wait on the airplane to make sure you get your on time departure on a 90 degree day. Insure there is air hooked up to the plane so passengers are safe and comfortable. Also some form of communication for the flight attendants to call the gate or ops in case of an emergency. This situation was not safe




Synopsis: Flight Attendant reported that airplane passengers were boarded onto a hot airplane with no air conditioning.