is an appeal to authority inherently a fallacy?

Relying on an authority to support a position doesn't make the position wrong; however, citing a presumed authority doesn't make the argument right, either.  If the only reason for holding a position is that some authority supports that position, the reasoning is weak.  

It would be useful to see why the authority supports the position and use that rationale as the basis of your argument.  Then, citing an authority that supports your view can strengthen your argument ... but only if you have an argument in the first place.

No. Not inherently.

The scientific method has five basic steps, plus one feedback step:
 1. Make an observation.
 2. Ask a question.
 3. Form a hypothesis, or testable explanation.
 4. Make a prediction based on the hypothesis.
 5. Test the prediction.

If you can reliably replicate the results, the category of the subject under study advances from hypothesis to theory. Then use the results (the feedback step) to make a new question, form new hypotheses and  predictions. All sciences use the scientific method. The scientists in different fields, of course,  ask different questions and perform different tests. However, they use the same core approach to find answers that are logical and supported by evidence. 

The purpose of a test experiment is to determine whether empirical observations agree with or conflict with the expectations deduced from the hypothesis. Expert disagreement should lead to debate which furthers knowledge on the issue and lead us closer to a correct answer by eliminating improbable interpretations.

What we reasonably seek is epistemological certainty, that is to say, the conclusion is based upon the available evidence. If more evidence appears or we consider a different way to analyze the current evidence, then the conclusion must change to conform to that.
 
Before trusting an expert, one must determine whether the expert’s claims are valid. A proper investigation should be transparent, objective, data-driven, inclusive of broad expertise, subject to independent oversight, and responsibly managed to minimize the impact of bias or conflict of interest.

I find it common for two scientists with good credentials to examine the same facts and come to different conclusions. So how do you know which one is right? You have to test the testimony. Otherwise, all you have is a one-sided monologue.

We cannot have a rule by experts, as all too many examples provide. There was a time, for example, when “all” the scientists believed the world was flat and the sun revolved around the earth. You would be imprisoned or killed to suggest otherwise. After all, that would be misinformation. 

But there is an issue beyond the experts. Even if an expert is correct in what the expert claims within his field of expertise, it can lead to tragedy. This is because each specialized group sees an ever-shrinking piece of the more giant puzzle of life and focuses on what is minutiae when analyzing the situation as a whole., i.e., the Big Picture. What is a reasonable course of action within their narrow field of expertise, is not reasonable when viewed as a part of the Big Picture. 

Experts tend to examine an issue only from the point of view of their own profession and then opine on areas in which they lack expertise.

Elon Musk described it: “The most common error of a smart engineer is to optimize a thing that should not exist.” pic.twitter.com/YCupAKTF1D. July 10, 2024.

The world learned this time and again. For example, during the Covid pandemic virologists were concerned only with the virus and not the more significant effects on human life. As a result, the cure became worse than the disease.

You do not need to be an expert in the field under discussion. But you do need to examine the evidence and the process upon which the experts claim to base their conclusion (opinion). The evidence that scientists bring to the table is critically important — not their conclusions —  otherwise, you have abnegated your mind to theirs. 

An appeal to authority is not inherently a fallacy, but it can become one depending on the context and how it is used. The appeal to authority, also known as "argumentum ad verecundiam," involves relying on the opinion or statement of an authority figure on a topic. Here are some points to consider regarding this:

1. **Legitimate Use**: Referring to an expert or authority in a particular field can be a valid and reasonable form of argument, especially if the authority's expertise is directly relevant to the issue at hand.

2. **Fallacious Use**: It becomes a fallacy if the authority is not an expert in the relevant field, if there is no consensus among experts, or if the authority's statement is taken as definitive without question or critical evaluation. Additionally, if an authority is cited to support a claim that is outside their area of expertise, this constitutes a fallacious appeal to authority.

3. **Critical Evaluation**: Even when an authority's opinion is invoked validly, it should be subject to critical evaluation. It's crucial to consider the evidence, potential biases, and the reasoning behind the authority's stance.

4. **Bias Awareness**: Be aware of cognitive biases, such as the bandwagon effect or appeal to tradition, which might lead someone to accept an authority's opinion without proper scrutiny simply because the authority is widely respected or customary.

By ensuring that the appeal to authority is used appropriately and in conjunction with sound evidence and critical thinking, it can be a strong component of a logical argument.

Not necessarily.

There are a lot of subjects that require a lot of time and specialized knowledge to understand, and a layperson who tries to do so will often make mistakes or miss details. It does, sometimes, become necessary to rely on the opinions of experts.

The way I typically avoid using it fallaciously is to, rather than finding an expert who agrees with me, see what the consensus among experts is, if there is one, and what degree of confidence the community of experts has in this opinion.