Incorrect hold entry due to chart confusion

On the descent into EGWU (Northolt) on the NUGRA 1H arrival we were told to expect holding for 10 minutes at Bovingdon (BNN). It was a very high workload phase of flight for us because not only where we constantly being vectored, we were also going in and out of very bumpy rain showers. The instruction given was just a few minutes prior to reaching BNN and was as follows: “Expect holding at BNN, 10-minute delay”.

Right away my co-captain diverted his attention to trying to find the published holding at BNN and showed me the Jeppesen chart for the NUGRA 1H. It was NOT immediately clear what the published holding pattern was. I told him to query approach about what they wanted us to do because we were quickly approaching BNN. I wondered if maybe they wanted us to hold on the missed approach hold from the EGWU ILS25 because it was off a radial from BNN. My co-captain’s query was “Do you want us to hold on the missed approach holding pattern off of BNN?” The reply we got was hold as published. At this point we should have asked for vectors because we couldn’t find the published holding pattern at BNN. Instead, we entered a hold south with 1-minute legs, right hand circuits. Approach asked us if we had entered holding to which we replied yes. They must have realized we entered the wrong hold because the next instructions were vectors for a 10 minute delay.

When we got on the ground, I realized something had gone wrong and opted to call the EGWU Tower to get clarification on the holding. After a few minutes of discussion, I realized my mistake; the Jeppesen Chart had a bubble note indicating published hold for BNN but it was not printed close to point of the hold. Because of the way our charts are displayed in the cockpit you must find the bubble note in a different portion of the screen (slew the view to a different portion of the chart) and it was missed. I asked my co-captain if he had ever seen these notes before on other charts and he had not. Unfortunately, I knew about this subtle change but missed it because of the increasing workload. In the end this was good reminder that if you are unsure of a clearance not to accept it until you are positive you know the instructions. The airspace was very busy but asking for a vector hold would have prevented this incorrect hold entry.

Ordinarily, crews inbound to Northolt do not hold at BNN and are given a vector for the approach so being asked to hold would have been unexpected. Furthermore, the Jeppesen charts for the procedure do indeed have the published hold pattern someway offset from the BNN location on the chart and so there is some sympathy for the crew (see screenshot with highlight arrow).  However, as part of their arrival brief, the crew should have made sure they knew what any potential hold procedure would be as they approached BNN and, if not clear what to do when instructed to hold, they should have asked the controller for more information or requested radar vectors.  Equally, although controllers were justified in assuming that the pilots would understood what was required when they were issued an instruction and did not query it, the controller could have asked whether the crew knew what was expected of them given that this was not a normal routing. Ultimately, the approach plate gives a warning ‘Do not proceed beyond BNN VOR without ATC clearance’ and so the crew ought to have conducted a self-briefing about what contingencies might result once they arrived at BNN in case they were not cleared to proceed beyond.