Chapter 3 — Light Streaks Off The Runway

Pham Nha Uyen did not talk about pencil lines in the morning meeting. She placed the map on the table, held the edge of the paper with a wrench, and waited for Nghi to open the book.

“What did you find out?” Nghi asked.

"The current map shows the cable from the south cabinet running straight out to the west lights. The old version had a loop."

"And?"

Uyen looked through the room door, where Tong was talking to the operator. “If I say the map is wrong, I'm afraid people will ask why my apprentice came to this conclusion.”

"I'm not concluding. I'm pointing out two different maps."

“So what do you say?”

“Say exactly what you see.”

Uyen opened the notebook and wrote: "Map A and map B do not coincide with the cable route in area W-3. It has not been determined which version is current."

“Add the source of each version,” Nghi said.

Uyen looked up. "Source?"

“Who founded it, what date, what was it used for?”

Uyen rummaged through a stack of documents. The current map has no revision date, only the electrical department stamp. The old version was recorded eight years ago, when the airport repaired the foundation after subsidence. The detour is marked with a red pen, next to the word "temporarily avoid".

“Does the old copy have the signer's name?” Nghi asked.

Uyen looks in the bottom corner. There are three signatures, one is Ngo Thanh Vuc.

Nghi recognized the handwriting immediately. Mr. Vuc once taught her how to hear the sound of a relay closing the circuit, how to smell burning plastic before seeing a spark, and how not to touch things you haven't identified with your fingers. In Nghi's memory, he always said one sentence: "The device does not lie. The person who reads it can read it wrongly."

“Do you know this person?” Uyen asked.

"Know."

“Who is he?”

“The person who was in charge of the department.”

“Is that the person who signed the map?”

"Have."

Uyen waited more, but Nghi closed the book. "Haven't called him yet. First measure the field."

Ho Boi Lan took them along the drainage ditch. She didn't carry a map, just a bamboo stick with ten centimeter segments marked. The stick is used to poke through mud, measure water, or as a support when walking across soft ground.

“Miss Lan, how much can the junction box translate?” Uyen asked.

"I don't know. But I know the soil around it has changed."

Lan poked her stick down the side of the stake. The tip of the stick went deeper into the swamp, then hit a hard layer. She changed positions and poked again.

"During the dry season, the water recedes, and during the windy season, the water accumulates. People who make drawings often measure when the ground is good," Lan said. “The ground here is not good.”

Measure pile tilt with handheld equipment. The error is small, but the tilt direction is in the same direction as the roundabout on the old map.

Uyen wrote.

A truck carrying materials passed by outside the inspection area. Kha uses a walkie-talkie to report airspace? Nghi corrected: "regional newspaper" and then found himself starting to mix up terminology out of habit. Kha stood at the landmark, raised his hand, and guided the car around. The driver asked why he had to detour when the road was clear.

“Because we are measuring something invisible,” Kha replied.

“Are you done measuring yet?”

"Not yet."

“When will it be over?”

“When the data is enough.”

Car passes by. Uyen looked at Kha. “You talk like Ms. Nghi.”

“I'm infected.”

At noon, Truong Dieu Han returned with a set of documents from the company. She did not sit in the operating room but went to the scene, wearing low shoes to avoid sinking. Han asked Nghi if he knew the reason.

"Not yet."

“If not, why do I hear so many people say this is just a perspective error?”

Nghi looked at Tong in the distance. He is talking with the cold storage team. “Because someone wants a short answer.”

Han opened the document. "The short answer can be very expensive. But the long answer must also indicate the next step."

Consider looking at the requirements table: check the magnetic light multiple points, check runway markings, check backup power, test low visibility conditions and write down who is responsible. The document does not say which system must be replaced. It just requires evidence for the crew to believe.

“The company needs an inspection from above,” Han said.

“We are not yet authorized to use the aircraft for an unknown system.”

"Not a passenger plane. Low-altitude observation device, with a licensed operator."

Nghi looked at Tong. He heard. "Expense?"

Han replied: "The company will share a portion if the airport commits that the data will not be retained just to protect the schedule."

Tong frowned. “Are you asking us to provide internal data?”

“I suggest we look at the same problem.”

Nghi didn't want the inspection to depend on the company's goodwill, but also knew the overhead view was the evidence they were lacking. She requested that the proposal be put in writing, with the possibility of cancellation if the weather was bad.

Han agrees.

In the afternoon, Uyen discovered that the last light poles were not at the same distance. She didn't just take a measuring tape; She placed landmarks on the background, photographed each segment and recorded the direction of view. From mark number three, the row of lights closes. From mark number five, the distance between the last two lights becomes wider.

“Miss Nghi,” Uyen called.

Nghi comes. Uyen spread two sheets of paper on the hood of the car, drawing a line connecting the points. One route follows the map, one route follows the field. They do not overlap.

“I think the light line is not wrong,” Uyen said. “It's just not on the road that people think it is.”

Nghi looked at her. "That's a good hypothesis. You should write it down as a hypothesis."

“I'm afraid of writing it down and people will tell me to infer it.”

“Inference is when you jump over the data. You're connecting the data to the question.”

Uyen added the line: “Hypothesis to test: landmarks and junction boxes move with the ground, while the operating map does not update.”

At the end of the day, Tong called Nghi into his room. He placed on the table the route opening schedule, cost table and an email from the province requesting "no unplanned warnings."

“I can't use hypotheticals to close the field,” he said.

“I haven't asked to close yet.”

“But you're creating a chain of records that will make people ask.”

“Yes. Because they need to ask.”

Tong looked at the photo Uyen took. “You think I want to hide it?”

“I think you want the schedule to run right.”

“And you think those two things can't coexist?”

“I think they only coexist if the cause is dealt with first.”

Tong was silent. He returned the photo to Nghi. "Tomorrow, I will allow four more hours of inspection. After that, there must be a provisional report."

“I also need the signature of the person at the scene.”

“You will.”

Nghi left the room. Uyen was waiting in the hallway, holding a map. She asked: “Is he angry?”

"Have."

“Are you scared?”

Nghi looked at the lights through the glass window. "Have."

“So why do you still do it?”

"Because I'm afraid it's not data. It's just a signal reminding me to check more closely."

Uyen looked at her drawing. The two curves run parallel, then separate at the bottom of the page.

Outside on the runway, the four lights lit up a beat as the sun had just set.

Nghi also called the maintenance unit's foundation measurement technician, Mr. Phuc Lam. He carried a subsidence meter and a worn manual. Lam did not promise to give an answer within the same day. He just said the device needs a stable background and three readings at the same mark.

“What if the foundation is unstable?” Uyen asked.

“It's unstable.”

"But I need a number.”

“A measurement on a translating platform without conditions written on it only gives the reader false confidence.”

Nghi looked at Uyen. “Did you hear that?”

Uyen nodded. Isolate the "landmark status" column.

Lam measured peg number three, then peg number five. The difference is not large, but the direction changes in the same direction as the ditch. He requested that a reference marker be placed on the concrete foundation near the station. The distance from the reference marker to the field stake changes after each heavy vehicle passes.

Kha heard this and immediately proposed to move the car at an unscheduled time frame. Please ask about the cost. Kha gave the bus timetable and inspection time without saying "temporarily avoid".

“From 6 p.m. to 9 p.m., cold storage trucks are heaviest,” Kha said. “If you want to measure accurately, you need to change the delivery time or measure at night when there are fewer vehicles.”

Tong looked at Han. “Can the company change the delivery door?”

Han called cold storage and talked for nearly ten minutes. As a result, they can stock part of the goods sooner, but at the cost of paying extra shifts. Cold storage agrees for one day, not long term.

Nghi clearly stated: “Measurement plan affects labor schedule; Not called no impact.”

Phuc Lam looked at that sentence. “You often write down parts that other people don't want to see.”

“Because that part usually comes back as an error.”

In the evening, Uyen compiles location data. She placed two lines: the painted edge line and the line connecting the candlesticks. Distances outside the W-3 zone all fluctuate slightly. At the last four lights, the distance widens in the direction of the pile's tilt. When the backup power is on, the light streak in the image changes rhythm but does not change direction.

“I think these are two layers of problems,” Uyen said. “One layer is the underlying geometry; one layer is the time the lights are on.”

Nghi replied: “That is a better hypothesis than 'the light is wrong'.”

“But if both are right, it will be difficult to fix.”

“Correcting difficulty does not make the data less accurate.”

Uyen no longer asked if she should speak. She herself sent the board to Duy, Han and Lan, clearly stating "working version, not approved yet".

Tong called Nghi after reading. “I saw Uyen send documents to the company.”

“Working version, with notes.”

“I haven't signed to share yet.”

“Data is not my private property. If it is limited, please clearly state the scope.”

Keep quiet. “I will make the rules.”

"Good."

“Can you not say that every time I suggest an improvement?”

“If the improvement is right, you don't need to say anything.”

The call ended. Nghi knew she had just made Tong uncomfortable, but she also knew that discomfort was not the criterion to keep a person quiet.

In the afternoon, Han confirmed that the observation equipment would arrive tomorrow. Lan prepares the way. Kha prepares the restricted area. Duy arranged the choir tower. Everything begins to have names and times, but the streak of light still has no final cause.

Uyen pasted the transparent map on the board. Two curves are no longer just her exercise. It became a question that the entire airport had to answer.