When boarding the Singapore Airlines Airbus A350-900XWB from Singapore's Changi Airport, we found that our Huawei P10 phone was low on battery and needed a quick charge. In economy class, Singapore Airlines offers two USB Type-A connectors next to each seat's personal screen, allowing for easy charging of any device. Let's see how much power is actually available from each of the USB Type-A connectors.
When the Huawei P10 is first plugged into the USB Type-A connector that has the lightning bolt symbol, implying fast charging, we used the GRL-USB-PD-A1 analyzer by Granite River Labs to observe charging when the phone was at a 33% battery level. In the first 10 seconds, charging initiated at around 5 volts as the phone started pulling about 0.9 amps current while switched on. At almost 70 seconds, while the phone was asleep, it pulled higher current to draw around 7.3 watts (4.9 volts @ 1.5 amps) charging power.
We then connected the 33% charged Huawei P10 to the other USB Type-A port that didn't have the lightning bolt symbol. The phone was seen to draw power of only about 3.8 watts (4.8 volts @ 0.8 amps), which is expectedly much lower than the 7.3 watts that the phone received over the fast charging port.
The USB Type-A port that has the lightning bolt symbol seems to support the 1.5 amps allowed by USB Battery Charging 1.2 while the other USB Type-A port only allows up to .9 amps.
Of course, if you need even faster charging, you should connect a USB Power Delivery based charger or Huawei's own SuperCharge charger for 15 watts of charging.